Transcript Chapter 28: Reproductive System

Chapter 28:
The Reproductive System
BIO 211 Lab
Instructor: Dr. Gollwitzer
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• Today in class we will:
– Identify the organs and anatomical structures of the
male reproductive system
• Testes
– Spermatic cords
– Inguinal canals
– Seminiferous tubules
– Spermatogenesis
• Reproductive tract
– Epididymis
– Ductus deferens
– Urethra
• Accessory glands
– Seminal vesicles
– Prostate gland
– Bulbourethral glands
• External genitalia
– Scrotum
– Penis
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What does it include?
• Gonads:
– Organs (testes and ovaries) that produce gametes (sperm
and eggs) and hormones
• Ducts:
– Receive and transport gametes
• Accessory glands:
– Secrete fluids into ducts
• External genitalia:
– Perineal structures associated with reproductive system
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Male Reproductive System
Figure 28-1, 7th edition
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Descent of the Testes
• Testes form inside body cavity adjacent to kidneys
• Move into lower abdominopelvic cavity
• Then into scrotum between 7 months and birth
Figure 28–2b, 7th edition
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Male Reproductive System:
Spermatic Cords
• Extend between abdominopelvic cavity and testis:
– Consist of layers of fascia and muscle
– Pass through inguinal canal
– Descend into scrotum
• Surround:
– Ductus deferens
– Blood vessels:
• Testicular (gonadal) artery
• Pampiniform plexus of testicular vein
– Nerves
– Lymphatic vessels
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Male Reproductive System:
Inguinal Canals
• Passageways through abdominal musculature
• Form during development as testes descend into
scrotum
• Inguinal hernia:
– Presence of spermatic cord creates weak points in
abdominal wall
– May result in portion of intestine protruding into
inguinal canal and/or scrotum
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Figure 28-3
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Male Reproductive System:
Scrotum (External Genitalia)
• Pouch that encloses testis
• Divided internally into 2 chambers
• Raphe (seam) – partition between chambers marked by raised thickening on
scrotal surface
• Scrotal cavity – each testis lies in separate chamber; protects against spread of
infection from one testis to another
• Tunica vaginalis:
– Serous membrane that lines scrotal cavity
– Has parietal tunica vaginalis (lines scrotum) and visceral tunica vaginalis (covers
testes) – scrotal cavity lies in between
– Reduces friction between parietal and visceral surfaces
• Scrotal skin – thin layer with underlying superficial fascia
• Dartos muscle – smooth muscle within dermis; responsible for wrinkled
scrotal surface with resting muscle tone
• Cremaster muscle – skeletal muscle deep to dermis; contraction pulls testes
closer to body during sexual arousal or temperature change (cold)
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Male Reproductive System:
Testes
• Tunica albuginea:
– Dense layer of CT with many collagen fibers
– Deep to visceral tunica vaginalis covering testis
– Fibers extend into substance of testis forming fibrous partitions (septa)
• Septa - divide testis into lobules
• Lobules – contain seminiferous tubules
• Seminiferous tubules:
– Slender, tightly coiled tubules (total ½ mile)
– Site of sperm production
• Rete testis – passageway/structure formed by looped
seminiferous tubules
• Efferent ductules – connect rete testis to epidiymus
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Figure 28-4
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Male Reproductive System:
Seminiferous Tubules
• Delicate CT capsule surrounds each tubule
• Within spaces between ST are blood vessels and large interstitial
cells (Leydig cells)  androgens (testosterone)
• Within ST are sustentacular (Sertoli) cells:
– “Nurse cells”
– Are attached to tubular capsule and extend toward lumen between cells
– Form blood-testis/sperm barrier – regulate transport to lumen of ST
• Each ST contains cells undergoing spermatogenesis:
–
–
–
–
= process of spermatozoa production
Process begins at outermost layer of cells in ST
Proceeds toward lumen
At each step, cells move closer to lumen
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Male Reproductive System:
Spermatogenesis
• Spermatogonia (stem cells) – divide by mitosis 
– 1 Primary spermatocyte and 1 spermatogonium
• Primary spermatocyte:
– Begins meiosis = reduction division  ½ chromosome number
in gametes
–
• Secondary spermatocytes 
• Spermatids:
– Immature spermatozoa
– Spermiogenesis 
• Spermatozoa:
– Physically mature gametes, but functionally immature
– Depend on other portions of reproductive tract for functional
maturation
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Figure 28-5
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Male Reproductive System:
Reproductive Tract
• Epididymis:
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–
–
–
Start of male reproductive tract
Coiled tube (20+ ft!) bound to posterior border of testis
Where sperm complete maturation
Has 3 sections:
• Head – superior, proximal to testis; receives spermatozoa from
efferent ductules of testis
• Body – extends along posterior margin of testis
• Tail:
–
–
–
–
Inferior portion
Number of coils decrease
Where spermatozoa are stored
Recurves and ascends to connect with ductus deferens
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Figure 28-9
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Male Reproductive System:
Reproductive Tract
• Ductus (vas) deferens:
– Transports and stores sperm (for several months –
in state of suspended animation with low metabolic
rates)
– Begins at tail of epididymus and ascends through
inguinal canal into abdominal cavity
– Ampulla – expanded portion just before seminal
vesicles and prostate gland
– Ejaculatory duct – short segment; from junction of
ampulla with duct of seminal vesicle through
prostate gland to urethra
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Male Reproductive System:
Reproductive Tract
• Urethra:
– From urinary bladder to tip of penis
– Passageway used by urinary and reproductive
systems
– Divided into 3 regions:
• Prostatic
• Membranous
• Spongy (penile)
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Male Reproductive System:
Accessory Glands
•  fluid component of semen
• Seminal vesicles:
– Paired glands that contribute 60% of semen volume
– Secretions discharged into ejaculatory duct at emission (when peristaltic
contractions occur in ductus deferens, seminal vesicles and prostate
gland)
• Prostate gland:
– Small muscular gland that encircles urethra as it leaves bladder
– Contributes 20-30% of volume of semen
– Secretions ejected into prostatic urethra
• Bulbourethral glands (Cowper’s glands):
– Very small, round glands at base of penis (in urogenital
diaphragm/membrane)
– Empty into urethra
– Produce mucous secretion that lubricates tip of penis
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Figure 28-10a
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Male Reproductive System:
Penis (External Genitalia)
• Tubular, erectile organ through which urethra passes
• Functions:
– Conducts urine to exterior
– Introduces semen into female’s vagina during sexual
intercourse
• Divided into three regions:
– Root – fixed portion that attaches penis to body wall
– Body (shaft) – tubular, movable portion
– Glans – expanded distal end that surrounds external urethral
meatus
• Prepuce (foreskin) – fold of skin that surrounds tip of
penis; surgical removal = circumcision
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Male Reproductive System:
Penis (External Genitalia)
• Erectile tissue:
– Makes up most of body of penis
– Has vascular channels that become engorged with
blood in response to stimuli  erection
– 3 cylindrical columns of tissue:
• Corpora cavernosa (2) – erectile tissue that surrounds
central arteries
• Corpus spongiosum – surrounds penile urethra
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Figure 28-11
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• Today in class we will:
– Identify the organs and anatomical structures of the
female reproductive system
• Mesentery structures
• Ovaries
– Oogenesis
• Ovarian structures after ovulation
• Uterus
– Uterine wall
– Uterine tubes
– Vagina
• External genitalia
–
–
–
–
–
Clitoris
Prepuce
Vestibular/Bartholin glands
Labia majora
Mons pubis
• Mammary glands
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Female Reproductive System
Figure 28-13, 7th edition
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Female Reproductive System:
Mesentery Structures
• Broad ligament:
– Extensive mesentery that encloses ovaries, uterine
tubes and uterus
– Attaches to sides and floor of pelvic cavity,
continuous with parietal peritoneum
– Limits side to side movement and rotation
• Mesovarium – thickened fold of mesentery
that supports and stabilizes each ovary
• Ovarian ligament – attaches ovary to uterus
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Figure 28-14a, 7th edition
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Female Reproductive System:
Ovaries
• Small, paired organs near lateral walls of pelvic cavity
• Position stabilized by:
– Ovarian ligament – extends from uterus to ovary
– Suspensory ligament – from ovary to pelvic wall; contains ovarian vein and
artery (connected to ovary at ovarian hilum; where ovary attaches to
mesovarium)
• Appearance:
– Pink or yellowish
– Nodular consistency
• Tissue layers:
– Visceral peritoneum (germinal epithelium) – overlies …
– Tunica albuginea – dense CT layer
– Stroma – internal tissue; consists of:
• Cortex - site of oogenesis = oocyte/gamete production
• Medulla
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Female Reproductive System:
Oogenesis
• Oogonia (stem cells):
– Formed before birth
–  primary oocytes (daughter cells) between mo 3-7
in utero
• Ovarian follicles:
– Specialized stuctures in cortex of ovaries
– Where oocyte growth and meiosis I occur
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Female Reproductive System:
Oogenesis
• Oogonia  primary occyte
• Primordial follicle surrounds primary oocyte (grouped in egg
nests)
• Primary follicle formed:
– Follicle cells around primary oocyte become granulosa cells
– Surrounded by thecal cells
• Secondary follicle formed:
– Primary oocyte still present
– Follicle accumulates follicular fluid
• Tertiary follicle formed:
– Has an antrum (expanded central chamber) surrounded by granulosa cells
– Primary oocyte  secondary oocyte just before ovulation
– At ovulation tertiary follicle releases secondary oocyte
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Female Reproductive System:
Ovarian Structures After Ovulation
• Corpus hemorrhagicum:
– Formed when empty tertiary follicle collapses, ruptured
vessels bleed into antrum
• Corpus luteum (CL):
– Remaining granulosa cells divide and form a “yellow body”
– Remains if pregnancy occurs
– Degenerates approx 12 days after ovulation if no pregnancy
• Corpus albicans:
– Fibroblasts invade nonfunctional CL  pale scar tissue (“white
body”
– = end of ovarian cycle
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Figure 28-16-5
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Female Reproductive System:
Uterine Tubes
• aka fallopian tubes, oviducts
• Hollow, muscular tubes
• Divided into three segments:
– Infundibulum:
• End closest to ovary
• Funnel-shaped with finger-like projections (fimbriae)
that extend into the pelvic cavity
– Ampulla – middle segment
– Isthmus - short segment connected to uterus
– NOTE: fertilization usually occurs in region
between ampulla and isthmus
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Figure 28-17a, 7th edition
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Female Reproductive System:
Uterus
• Small, pear-shaped organ
• Stabilized by suspensory ligaments
• Regions:
– Body (corpus):
• Largest portion of uterus
• Ends at isthmus (constricted region)
• Fundus – rounded portion superior to attachment of uterine tubes
– Cervix:
• Inferior portion that extends from isthmus to vagina
• Cervical os:
– External orifice of uterus that leads into the cervical canal
• Cervical canal:
– Passageway opening to uterine cavity
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Female Reproductive System:
Uterine Wall
• Myometrium:
– Thick, outer muscular layer
– Makes up 90% of uterus
• Endometrium:
– Thin, inner mucosa with glands and blood vessels
– Sloughed during menses (periods)
• Perimetrium:
– Incomplete serous membrane covering fundus and
posterior surface
– Continuous with peritoneal lining
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Figure 28-18
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Female Reproductive System:
Vagina
• Elastic, muscular tube
• Between cervix and vestibule (= space bounded by
female genitalia)
• Rugae – folds on epithelial surface
• Fornix – shallow recess that surrounds cervical
protrusion into vaginal canal
• Hymen – elastic epithelial fold that partially/
completely blocks entrance to vagina before onset of
sexual intercourse
• Vestibular bulbs – masses of erectile tissue on either
side of vaginal entrance; same embryological origin
as corpus spongiosum of penis
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Female Reproductive System:
Vulva
• Vagina opens into central space (vestibule) bounded
by small folds, the labia minora
• Clitoris – anterior to vaginal opening; small rounded
tissue projection equivalent to penis; contains erectile
tissue
• Prepuce – extensions of labia minora that surround
clitoris
• Vestibular (Bartholin) glands – same embryological
origin as bulbourethral glands in males; lubricates
vaginal area
• Labia majora – larger folds that encircle labia minora
• Mons pubis – adipose tissue deep to skin anterior to
the pubic symphysis
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Figure 28-22
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Analogous Reproductive
Organs/Tissues
Males
Females
Testes
Ovaries
Penis
Clitoris
Corpora cavernosa
Erectile tissue
Corpus spongiosum
Vestibular bulbs
Proximal shaft
Labia minora
Penile urethra
Vestibule
Bulbourethral glands
Greater vestibular glands
Scrotum
Labia majora
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Mammary Glands
• Specialized organs (exocrine glands) of the
integumentary system
• Controlled by hormones of the reproductive system
and placenta
• Lie in subcutaneous tissue of pectoral fat pad
• Structures:
– Nipple – where mammary ducts open to surface
– Areola – reddish brown skin around nipple; contains large
sebaceous glands
– Lobes – make up glandular tissue
– Lactiferous ducts – formed by converging ducts from
several lobes; 15-20/ nipple
– Lactiferous sinus – expanded chamber formed by
enlargement of lactiferous duct near nipple
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Figure 28-23a
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