Slide 1

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 2

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 3

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 4

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 5

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 6

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 7

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 8

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 9

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 10

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 11

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 12

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 13

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 14

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 15

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 16

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 17

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 18

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 19

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 20

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 21

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 22

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 23

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 24

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 25

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 26

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 27

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 28

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 29

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 30

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 31

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 32

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 33

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 34

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 35

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 36

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 37

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 38

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 39

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 40

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 41

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 42

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 43

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 44

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 45

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 46

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 47

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 48

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 49

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 50

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 51

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 52

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 53

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 54

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 55

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 56

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 57

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 58

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 59

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 60

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 61

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 62

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 63

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 64

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 65

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 66

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 67

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 68

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 69

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 70

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 71

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 72

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 73

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 74

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 75

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 76

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 77

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 78

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 79

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 80

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 81

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 82

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 83

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 84

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 85

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 86

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 87

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 88

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 89

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 90

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 91

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 92

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 93

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 94

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 95

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 96

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 97

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.


Slide 98

CORE-RS-05
Reproductive System &
Development
Robert F. Allen

Functions: Urination and
Copulation

Penis

Functions: Transport urine &
semen

Bladder

Urethra

Function: Maintain temperature of
testes approx. 30 C below normal
body temp.

Scrotum

Function: Produce sperm and
testosterone

Testis

Function: Produce Sperm

Seminiferous Tubules

Testis

Testis Cross Section

Interstitial Cells
Produce Testosterone

Function: Sperm storage and
maturation

Epididymis

Function: Transport sperm to
urethra

Vas Deferens

Function: Produce 60% of
alkaline semen including fructose
to provide energy for sperm.
Seminal
Vesicles
Ejaculatory Duct

Function: Produces up to 1/3 of the
semen & includes nutrients &
enzymes to activate sperm.

Prostate

Function: Secretes mucous &
alkaline buffers to neutralize acidic
conditions of urethra.

Cowper’s Gland

Function: Receives penis &
semen and serves as birth canal
& passage for menstrual flow.

Vagina

Function: Provides passageway
for sperm, receives blastocyst,
retains & nourishes fetus &
expells fetus at term.

Uterus

Function: Cervical mucosa secretes
mucous blocking cervical canal
entrance to uterus.

Cervix

Function: Uterine lining in which
implantation occurs.

Endometrium

Function: Muscular contractions.

Myometrium

Function: Passageway for oocyte
and site of fertilization.
Uterine Tubes

Function: Produce oocytes & the
hormones estrogen and
progesterone.
Ovaries

Function: Sweep ovarian surface
to draw oocyte into ovarian tube.
Fimbriae

Mechanisms of Hormonal Action
• Direct Gene Activation
–
–
–
–

lipid soluble, steroid hormones
diffuse through cell membranes
bind to intracellular receptor
activated hormone receptor/complex binds with
gene, turning it on
– gene transcribes mRNA
– ribosomes use mRNA to synthesize enzymes to
stimulate cell activity or synthesize structural
proteins to be excreted or used within the cell

Direct Gene Activation
Steroid Hormone

Receptor/hormone Complex

Direct Gene Activation

Receptor/hormone Complex
Protein

mRNA

Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Thyroxine

Mechanisms of Hormonal Action
• Second Messenger Systems
–
–
–
–

amino acid & protein based
cannot pass through cell membranes
bind to cell membrane receptors
activate G proteins in membrane to produce
cyclic AMP in cytoplasm
– cyclic AMP acts as second messenger inside
cell activating protein kinases
– protein kinases trigger cellular responses

Second Messenger Systems

Hormone Sources & Functions
• Gonadotropin-releasing
Hormone (GnRH) :
– Source:

Hypothalamus

– Targets & Functions:
• Females & Males - Anterior Pituitary
– Stimulates the production of Follicle
Stimulating Hormone (FSH) &
Leutinizing Hormone (LH)
– Regulates the release of FSH & LH by the
anterior pituitary gland

Hormone Sources & Functions
• Follicle Stimulating Hormone:
– Source:

Anterior Pituitary

– Targets & Functions:
• Females - Ovaries
– Stimulates follicle growth & maturation
– Stimulates estrogen production

• Males - Seminiferous Tubules
– Promotes sperm production
(Spermatogenesis) by establishing
testosterone receptors on tubules

Leutenizing Hormone:
• Source: Anterior Pituitary
– Targets & Functions:
• Females - Ovaries
– Stimulates primary oocyte to complete
first meiotic division to become secondary
oocyte
– Triggers ovulation of secondary oocyte
– Transforms ruptured follicle into corpus
luteum
– Stimulates production of progesterone by
corpus luteum

Corpus luteum

• Males - Seminiferous Tubules
– Stimulates sperm production
(Spermatogenesis) by causing interstitial
cells in testes to secrete testosterone

Estrogen:
• Sources: Maturing Follicles & Corpus Luteum
– Targets & Functions:
• Body in general
– Stimulates the development of female
secondary sexual characteristics

• Uterus
– Stimulates proliferative phase of uterine
cycle

• Ovaries
– Promotes oogenesis

• Breasts
– Stimulates development of milk ducts and
sinuses (ampullae)

• Anterior Pituitary
– Stimulates burst-like release of LH

Progesterone:
• Source: Corpus Luteum & Placenta
– Targets & Functions:
• Females - Uterus
– Maintains thickened endometrium
– Stimulates nutrient release
– Quiets myometrium

• Females - Breasts
Corpus luteum

– Stimulates development of alveoli for milk
production

• Females - Anterior Pituitary
– Inhibits production & release of FSH &
LH

Testosterone:
• Sources: Interstitial Cells in Testes
– Targets & Functions:
• Body in general
– Stimulates the development of male secondary
sexual characteristics including:
» development of male genitalia
» male skeleton and muscle development
» male patterns for hair growth
» increased RBC production & higher
metabolic rate

• Seminiferous tubules

– Necessary for the completion of
spermatogenesis

• Anterior Pituitary
– Moderate inhibition of pituitary and
hypothalamus

Oxytocin:

• Sources: Manufactured by
hypothalamus. Stored &
released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex

– Targets & Functions:
• Uterus
– Stimulates contraction of uterine myometrium
causing lowering of fetus & labor

• Breasts
– Stimulates contraction of milk ducts and
sinuses, releasing milk

Prolactin:
• Source: Anterior Pituitary
– Targets & Functions:
• Breasts
– Stimulates alveoli of breasts to produce milk

• Regulation
– Release of prolactin by anterior pituitary is
regulated by hypothalamus production of
Prolactin Releasing Hormone (PRH) &
Prolactin Inhibiting Hormone (PIH)

Human Chorionic Gonadotropin:
• Source: Trophoblasts of blastocyst &
Chorion
– Target & Functions:
• Corpus Luteum
– Maintains corpus luteum & causes it to continue
producing progesterone in the absence of LH through first
four months of pregnancy till placenta produces sufficient
estrogen & progesterone to maintain the pregnancy

Hormonal Regulation of
Ovarian & Menstrual Cycles
1. Hypothalamus releases
GnRH.

2. GnRH stimulates anterior
pituitary to release FSH.
Estrogen
FSH

3. FSH stimulates a follicle
to grow & produce
estrogen.

Hormonal Regulation of
Menstrual & Ovarian Cycles
LH

4. Rising levels of estrogen
cause anterior pituitary to
increase production &
storage of LH.

Estrogen
Estrogen
FSH

Hormonal Regulation of
Menstrual & Ovarian Cycles
5. High estrogen causes LH
to be released in a burst &
the endometrium to thicken
(proliferative phase).

Estrogen
Estrogen
FSH

6. High LH stimulates first
meiotic division of primary
oocyte.

LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
7. High LH triggers
ovulation.

Estrogen
8. High LH causes
ruptured follicle to become
a corpus luteum.

Estrogen
FSH
LH

Hormonal Regulation of
Menstrual & Ovarian Cycles
9. Corpus luteum produces
progesterone.
10. Progesterone inhibits
the production of FHS &
LH by the anterior
pituitary & stimulates
secretory phase .

Estrogen

X

FSH

X
LH

Estrogen

Progesterone

Hormonal Regulation of
Ovarian & Menstrual Cycles
11. Diminishing levels of FSH
& LH cause corpus luteum to
deteriorate & produce less
progesterone.
12. Dimishing levels of
estrogen & progesterone
cause inhibition of FSH &
LH to end & thickened
endometrium to slough
(menses).

Estrogen
X
FSH

Progesterone
X

LH

X

Hormonal Regulation of
Ovarian & Menstrual Cycles

13. Increasing levels of
FSH cause a new cycle to
begin.

FSH

Hormonal Regulation in
Pregnancy

Normally dimishing levels
of estrogen & progesterone
from deterioration of the
corpus luteum would cause
thickened endometrium to
slough (menses) which
would terminating a
pregnancy.

Estrogen
X

Progesterone
X

X

Hormonal Regulation if
Pregnancy Occurs
Blastocyst produces
human Chorionic
Gonadotropin (hCG)
hormone which maintains
corpus luteum in the
absence of FSH & LH for
the first trimester.

Eventually the placenta
will produce sufficient
estrogen & progesterone to
sustain the pregnancy.

hCG

Mitosis
Interphase

Prophase

Metaphase

Mitosis
Anaphase

Telophase

Interphase

46

46

• Most cells of the body - growth, replacement, healing.
• No change in the number of chromosomes within each cell.

Meiosis

46

Interphase

Prophase

Metaphase

Meiosis

23
23
Reduction Division
Anaphase

Telophase

Interphase

Meiosis

23

23

23

23

23

23

• Only in gonads.
• Synapsis & shuffling of genetic information providing variation.

• Results in reduction of number of chromosomes by half (haploid).

Mitosis/Meiosis Comparison
46

46

23

46

46

23

23

23 23

23

Gametogenesis:
Process through which gametes are formed
• Spermatogenesis:
– produces male
gametes (sperm)
– occurs in the
seminiferous tubules
of the testes
– involves meiosis
– occurs throughout life
after puberty
– may produce
400,000,000 per day

• Oogenesis:
– produces female
gametes (oocytes)
– occurs in the ovaries
– involves meiosis
– occurs after puberty
until menopause
– humans normally
produce one oocyte
during each ovarian
cycle

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)

Meiosis I

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Secondary Spermatocytes (23)
Early Spermatids (23)

Meiosis I

Meiosis II
Spermiogenesis

Late Spermatids (23)

Spermatogenesis
Spermatogonium (46)
Mitosis

Daughter Cells (46)
Growth

Primary Spermatocyte (46)
Meiosis I
Secondary Spermatocytes (23)
Meiosis II
Early Spermatids (23)
Spermiogenesis
Late Spermatids (23)

(Lumen)
Spermatozoa (23)

Oogenesis
Oogonium (46)
(Mitosis)
Primary Oocyte (46)

Primary Oocyte (46)

Oogenesis
Oogonium (46)
(Mitosis)

Polar Body (23)

Primary Oocyte (46)
(Meiosis 1)
Secondary Oocyte (23)
Fertilization
(Meiosis 2)

Ovulation

Definitions & Functions Relative
to Reproduction

• Hypothalamus:

– Produces GnRH which stimulates the
production of FSH & LH by the anterior
pituitary gland initiating the ovarian cycle.
– Produces Oxytocin which is stored in the
posterior pituitary gland.

• Posterior Pituitary:
– Stores & releases hormone Oxytocin to
stimulate uterine contractions (Braxton
Hicks) & the milk let-down reflex.

Definitions & Functions Relative
to Reproduction

• Anterior Pituitary:

– Produces hormone FSH which stimulates the
growth & maturation of a follicle, the
production of estrogen in females and
stimulates sperm production in males.
– Produces & stores hormone LH which
causes first meiotic division of primary
oocyte, stimulates ovulation, causes the
development of and the production of
progesterone by the corpus luteum
– Produces & stores hormone Prolactin which
promotes lactation .

Definitions & Functions Relative
to Reproduction

• Spermatogonium:

– Primordial germ cell in seminiferous tubules
of testes from which sperm are produced.

• Oogonium:
– Primordial germ cell in ovaries of fetus from
which primary oocytes in follicles are
produced.

• Follicle:
– Sack-like structure in ovary containing an
oocyte surrounded by one or more layers of
cells which produces the hormone estrogen.

Definitions & Functions
Relative to Reproduction

• Mitosis:

– Process through which the nucleus of body
cells divide to produce identical daughter
cells for maintenance, healing & growth.

• Meiosis:
– Process through which gametes are formed
with half of the normal number of
chromosomes for sexual reproduction.

• Ovum:
– Functional female gamete which has
completed the first and second meiotic
divisions to become haploid.

Definitions & Functions Relative
to Reproduction

• Spermatozoan:

– Haploid male gamete which has completed
meiosis 1 & 2, spermiogenesis & is capable of
fertilizing a female secondary oocyte.

• Fertilization:
– Process through which haploid male &
female gametes fuse to form a diploid
zygote.

• Polar Bodies:
– Nonfunctional haploid female cells with little
to no cytoplasm produced in meiosis.

Definitions & Functions Relative
to Reproduction

• Hormone:

– Chemical messenger which is used to
regulate reproductive cycles and activities.

• Semen:
– Mixture of sperm and fluids from male
reproductive glands which supplies energy,
neutralizes acidic conditions in the
reproductive tracts and activates sperm.

• Hyaluronidase:
– Enzyme in acrosome of sperm that enables
sperm nucleus to enter the female gamete.

Preembryonic Development

Bone Formation

Definitions & Functions
• Zygote:
– A fertilized ovum which is diploid.

• Cleavage Divisions:
– Mitotic divisions of the zygote to increase the
number and surface area of cells in a
preembryo (2 cell, 4 cell, 8 cell, etc.)

• Morula:
– A berry shaped cluster of preembryonic cells
produced from cleavage divisions .

Definitions & Functions
• Blastocyst:
– A fluid filled sphere of cells formed from
the morula which implants in the
endometrium.

• Inner Cell Mass:
– A group of cells inside of the blastocyst
from which the three primary germ layers
will develop.

• Trophoblast:
– One of the cells making up the outer wall
of the blastocyst which will form the
chorion.

Definitions & Functions
• Chorionic Villi:
– Finger-like growths of the trophoblasts
into the endometrium to form the
placenta.

Definitions & Functions
• Chorion:
– Outermost embryonic membrane which
forms the placenta & produces human
chorionic gonadotropin.

Definitions & Functions
• Amnion:
– Membrane which surrounds embryo to
form the amniotic cavity & produces
amniotic fluid.

Definitions & Functions
• Amnionic Fluid:
– Protects fetus from trauma & permits free
movement without adhesion.

Definitions & Functions
• Yolk Sack:
– Provides initial nutrients, supplies earliest
RBCs and seeds the gonads with
primordial germ cells.

Gastrulation
• Preembryo becomes embryo as three
primary germ layers form.

Prembryo

Embryo

Ectoderm Derivatives
• Brain, spinal cord, nerves
• Cornea & lens of eyes
• Outer skin & accessory structures
– hair
– nails

• Enamel of teeth
• Linings of nasal & oral cavities & anal
canal

Endoderm Derivatives
• Epithelial lining of digestive tract
• Liver and pancreas
• Epithelial lining of respiratory tract &
tonsils
• Epithelial lining of reproductive ducts &
glands
• Thyroid, parathyroid & thymus glands
• Epithelial lining of bladder & urethra

Mesoderm Derivatives
• Muscle: skeletal, cardiac & smooth
• Connective tissues: cartilage, bone,
adipose
• Bone marrow, blood & lymphatic tissues
• Endothelial linings of blood & lymphatic
vessels
• Visceral peritoneum of organs in ventral
cavity
• Fibrous & vascular tunics of eyes
• Organs of urogenital system: kidneys,
gonads & reproductive ducts

Placental Function

Minerals Glucose
O2 Vitamins

Placental Function

Alcohol

Fetal Alcohol Syndrome
• Prenatal & postnatal growth retardation
• CNS involvement:
– neurological abnormalities
– developmental delays

•
•
•
•

Alcohol related birth defects
Mental retardation
Speech & hearing impairment
Learning, attention & memory deficits

Placental Function

Urea

CO2

Wastes

Placental Function - Smoking

CO CO2

O2

Nicotine

Smoking During Pregnancy
• Increases risk of ectopic pregnancy
• Doubles risk of placenta previa &
abruptio placenta
• Slows fetal development
• Doubles risk of low birthweight babies
• Increases risk of preterm deliveries
• Increases risk of cleft palate & lip
• Doubles risk of sudden infant death
syndrome (SIDS)

Drug Use

Antibiotics Nicotine
Crack

Irradiation
• High-energy
– X-rays
– Gamma rays

• Penetrate deeply into tissues causing
ionization of molecules.
• May directly or indirectly affect the
genetic material resulting in point
mutations (affecting a single base).
• May break chromosomes causing
deletions or translocation of genetic
information.

Placenta abruptio
• Any amount of placental separation prior
to delivery.
• Causes & Risk Factors:
–
–
–
–
–

Abdominal trauma
Hypertension during pregnancy
Diabetes mellitus
Cigarette smoking
Alcohol use during pregnancy

Placenta previa
• Placental growth across or adjacent to
opening of cervical canal in the uterus.
• Risk Factors:
– The number of prior pregnancies
– Multiple pregnancies (twins/triplets)
– Prior C-section where scar is close to cervix

• Symptoms:
– Spotting during 1st & 2nd trimesters
– Sudden, painless & profuse vaginal bleeding

Ectopic Pregnancy
• Implantation of blastocyst anywhere other than
within the uterus.
• Causes & Risk Factors:
– Physical blockage of uterine tube.
– Scarring of uterine tube by prior tubal
infection (pelvic inflamatory disease).
– Pregnancy following tubal ligation reversal
or despite oral contraceptive use.
• Symptoms:
– Lower abdominal or pelvic pain.
– Mild cramping on one side of pelvis.
– Abnormal vaginal bleeding (spotting).

Gonorrhea
• Bacterial Pathogen: Neisseria gonorrhoeae

• Transmission:
Sexual contact with
infected person or contact with bacteria in
the birth canal of an infected mother.

Gonorrhea
• Pathology: Inflammation of skin & mucous
membranes of urinary & reproductive
organs.

• Females: Painful urination, abdominal pain,
pelvic inflammatory disease, & sterility.
• Males: Painful urination with purulent
discharge & possible sterility.

Gonorrhea
• Babies: Contract bacteria in birth canal of
infected mother.

• Congenital Effects: Conjunctivitis &
blindness.
• Treatment: Ceftriaxone & Tetracycline
– Silver Nitrate in eyes of infants

Syphilis
• Bacterial Pathogen: Treponema pallidum

• Transmission: Sexual & transplacental
contact.

Primary Syphilis
• Incubation period - 21 days (average)
• Painless chancre (lesion) where bacteria
enter mucous membranes or skin.

• Spontaneously heals after 3 to 8 weeks.

Secondary Syphilis
• Fever, influenza-like symptoms, swollen
lymph nodes & skin rash.

• Without treatment, these symptoms may last
several weeks & disappear or death may occur.

Tertiary Syphilis
• Involvement of the skin, cardiovascular and
nervous systems.

• Gummas develop in infected tissues.

• Treatment of Choice:

Penicillin.

Congenital Syphilis
• Transplacental transmission.

• Stillborn, infective skin lesions, deafness,
impaired vision, Hutchison’s teeth, & skeletal
deformities .

Chlamydia

• Most prevalent STD in US.
• Bacterial Pathogen: Chlamydia trachomatis
• Pathology: Nongonococcal urethritis resulting in
serious reproductive tract complications (up to 80%
asymptomatic)
– pelvic inflamatory disease
– infertility
– ectopic pregnancy

• Babies infected in birth canal
– chlamydial opthalmia & pneumonia

• Treatment:

Tetracycline

Genital Herpes
• Pathogen:
Herpes Simplex Virus - Type 2
• Transmission by secretions from lesions.
• Crops of vesicular lesions occur on & around
genitalia.
• Lesions are recurrent (as often as 4 weeks) &
lead to painful ulcerations.
• Associated with higher than normal cervical
cancer with a 50% mortality rate in infected
women.
• Transplacental transmission to fetus.
• Treatment: Acyclovire to reduce symptoms.

Acknowledgements
Most of the figures used in this presentation came from the Benjamin Cummings Digital Library
Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public
domain internet sources and software in the possession of the author.