Transcript الشريحة 1 - shsmu.edu.cn

Physiology of Reproduction(II)
Teng Yincheng
M.D., Ph.D., Professor
Department Of Obstetrics & Gynecology
Renji Hospital Affiliated to SJTU School of Medicine
Pregnancy is defined as the course of embryo and fetal
growth and development in uterine
It begain at the fertilization and end the delivery of the fetal
and it’s attachment
Pregnancy occurs when a mature liberated ovum
is fertilized by a mature capacitated spermatozoon
The Sperm:
• The spermatozoa leave
the testis carrying 23
chromosomes but not
yet capable of
fertilization.
• Their maturation is
completed through their
journey in the 6 meters
of the epididymis and
when mixed with the
seminal plasma from the
epididymis, seminal
vesicle and prostate
gland.
The Sperm:
After semen is
ejaculated, the
sperms reach
the cervix by
their own motility
within seconds
leaving behind
the seminal
plasma in the
vagina
The Sperm:
At time of ovulation, the cervical mucous is in
the most favourable condition for sperm
penetration and capacitation as:
1. It becomes more copious, less viscous and
its macromolecules arrange in parallel chains
providing channels for sperms passage.
2. Its contents from glucose and chloride are
increased.
The Sperm:
• The sperms ascent through the uterine
cavity and Fallopian tubes to reach the
site of fertilization in the ampulla by:
1. Its own motility, and by
2. Uterine and tubal peristalsis which is
aggravated by the prostaglandins in the
seminal plasma.
The Sperm:
• The sperms reach the tube within
30-40 minutes
• But they are capable of fertilization
after 2-6 hours.
• This period is needed for sperm
capacitation.
Capacitation of sperms
• Is the process after which the sperm
becomes able to penetrate the zona
pellucida,that surrounding the ovum
and fertilize it.
• The cervical and tubal secretions are
mainly responsible for this capacitation.
Capacitation of sperms
• Capacitation is believed to be due to :
1.Increase in the DNA concentration in
the nucleus,
2.Increase permeability of the coat of
sperm head to allow more release of
hyaluronidase.
The ovum:
The ovum leaves the ovary after
rupture of the Graafian follicle,
carrying
23 chromosomes
and surrounded by the
zona pellucida and corona radiata.
The ovum:
The ovum is picked up by the
fimbrial end of the Fallopian
tubes and moved towards the
ampulla by the :
1. Ciliary movement of the cells and
2. Rhythmic peristalsis of the tube.
Fertilization:
• Millions of sperms
ejaculated in the vagina,
but only hundreds of
thousands reach the
outer portion of the
tubes.
• Only few succeed to
penetrate the zona
pellucida, and only one
spermatozoon enters
the ovum transversing
the perivitelline space.
Fertilization:
• After penetration of the ovum by a
sperm, the zona pellucida resists
penetration by another sperms due to
alteration of its electrical potential.
• The pronucleus of both ovum and
sperm unite together to form the zygote
(46 chromosomes).
Zygote
Sex Determination:
* The mature ovum carries 22 autosomes and
one X chromosome, while the mature
sperm carries 22 autosomes and either an
X or Y chromosome.
* If the fertilizing sperm is carrying X
chromosome the baby will be a female (46
XX), if it is carrying Y chromosome the
baby will be a male (46 XY).
Cleavage and blastocyst
formation:
On its way to the uterine
cavity, the fertilized ovum
(zygote) divides into 2,4,8
then 16 cells (blastomeres).
Cleavage and blastocyst
formation:
• This cleavage starts
within 24 hours of
fertilization and occurs
nearly every 12 hours
repeatedly
• The resultant 16 cells
mass is called morula
which reaches the
uterine cavity after
about 4 days from
fertilization.
Cleavage and blastocyst formation:
• A cavity appears within the morula
converting it into a cystic structure called
blastocyst.
• The cells become arranged into an :
1. Inner mass (embryoblast) which will form
all the tissues of the embryo, and an
2. Outer layer called trophoblast which
invade the uterine wall.
Cleavage and blastocyst
formation:
The blastocyst remains free in
the uterine cavity for 3-4 days,
during which it is nourished by
the secretion of the
endometrium (uterine milk).
Implantation
(nidation) :
The necessary
conditions of imbed
Disapearing of
the pellucid zone
 Syntrophoblast
formed from the blast
 Synchronizing development of blast
and the endometriun
 P Secretory enough
The stage of egg imbed
Apposition
Adhesion
Penetration
The decidua:
• It is the thickened
vascular endometrium
of the pregnant
uterus.
• The glands become
enlarged, tortuous
and filled with
secretion.
• The stromal cells
become large with
small nuclei and clear
cytoplasm, these are
called decidual cells.
The decidua, like
secretory
endometrium,
consists of three
layers:
1. The superficial
compact layer,
2. The intermediate
spongy layer,
3. The thin basal
layer.
The decidua
The trophoblast of the
blastocyst invades the
decidua to be
implanted in:
-The posterior surface of
the upper uterine
segment in about 2/3
of cases,
-The anterior surface of
the upper uterine
segment in about 1/3
of cases.
After implantation the
decidua becomes
differentiated into:
1. Decidua basalis; under
the site of implantation.
2. Decidua capsularis;
covering the ovum.
3. Decidua parietalis or
vera; lining the rest of
the uterine cavity.
The decidua
As the conceptus enlarges and fills the uterine cavity the decidua capsularis
fuses with the decidua parietalis
This occurs nearly at the end of 12 weeks
The decidua
The decidua has the following functions:
1.It is the site of implantation.
2.It resists more invasion of the trophoblast.
3.It nourishes the early implanted ovum by
its glycogen and lipid contents.
4.It shares in the formation of the placenta.
Chorion:
After implantation, the trophoblast differentiates
into 2 layers:
a. An outer one called syncytium (syncytiotrophoblast)
which is multinucleated cells without cell
boundaries,
b. An inner one called Langhan’s layer
(Cytotrophoblast) with simple cytoplasm.
• A third layer of mesoderm appears inner to the
cytotrophoblast.
Chorion:
• The trophoblast and the lining
mesoderm together form the
chorion.
• Mesodermal tissue ( connecting
stalk) connects the inner cell mass
to the chorion and will form the
umbilical cord later on.
Chorion:
• Spaces (lacunae) appear in the
syncytium, increase in size and fuse
together to form the
" chorio-decidual space" or
" intervillus space".
• Erosion of the decidual blood vessels by
the trophoblast allows blood to circulate in
this space.
Chorion:
• The outer syncytium and inner
Langhan’s cells form buds
surrounding the developing ovum
called primary villi.
• When the mesoderm invades the
center of the primary villi they are
called secondary villi.
• When blood vessels (branches from
the umbilical vessels) develop inside
the mesodermal core, they are
called
tertiary villi.
Primary villous
Secondary villous
Transverse section of tertiary villous
Chorion:
• At first, the chorionic villi surround the
developing ovum.
• After the 12th week, the villi opposite the
decidua capsularis atrophy leaving the
chorion laeve which forms the outer
layer of the foetal membrane and is
attached to the margin of the placenta.
• The villi opposite the decidua basalis
grow and branch to form the chorion
frondosum and together with the
decidua basalis will form the placenta.
• Some of these villi attach to the
decidua basalis ( the basal plate)
called the "anchoring villi", other hang
freely in the intervillus spaces called
"absorbing villi"
Amnion:
After implantation,
2 cavities appear
in the inner cell mass;
the amniotic cavity and yolk
sac and in between these 2
cavities the mesoderm
develops.
Development of embryo
and fetus
3 weeks
4 weeks
6 weeks
8 weeks
Attachment of the fetal
1.Placenta
2.Fetal membranes
3.Umbilical cord
4.Amniotic fluid
1.Placenta
It’s an exchange organ
between maternal and fetal
Amniotic membrane
chorion frondosum
Basal decidua
Round
Weight:450-650g
Diameter:16-20cm
Thickness:1-3cm
thick in center and thin
in margin
The functions of placenta
Gas exchange
Suply of nutrition
Depletion of fetal product of metabolisn
Defense function
Hormone synthesis
Human chorionic gonadotropin(HCG)
Human placental lactogen(HPL)
Pregnancy specific -glycoprotein(PS 1G)
Human chorionic thyrotropin(HCT)
Estrogen, P, Oxytocinase, heat stable alkaline
phosphatase(HSAP)
2.Fetal membrane
Chorion
Amnion
3.Umbilical cord
Length:30-70cm average:50cm
Consist of 2 artery and 1 vein
4.Amniotic fluid
Source: early from serum dialysis
late from fetal urine
Absorse: by fetal membrane, fetal
swallowing(500ml/day)
Amniotic exchange: between maternal
and fetal 400ml/h
Status of amniotic fluid
pH:7.20
Density:1.007-1.025
Contained: water(98-99%)
inorganic substance
organic substance(1-2%)
Volume of amniotic fluid
8 weeks:5-10ml
10 weeks:30ml
20 weeks:400ml
38 weeks:1000ml
The function of amniotic fluid
Protect maternal and fetal
Maternal changes during pregnancy
Isthmus: be dialated and become soft from 1cm
pre-pregnancy a portion of the uterus
after 12 gestational weeks
Cervix: be soft and coloration or stain
secrete amount of mucus avoiding the
uterus cavity suffer from infection
Changes of ovary
Stop ovulation
Corpus luteum formation and maintains for
10 weeks
And the function of corpus luteum is
substituted by the placenta
Corpus luteum atretic gradually after 3-4
months gestation.
2.Changes of the circulation
Heart border: become enlargement
Heart rate: increased 10-15 beat per min at the
late pregnancy
Heart volume: increased 10% at the late
pregnancy
Cardiac output
Very important for fetal growth and development
Incrased begain 10 weeks and upto the peak at 32 weeks
80ml/bp and keeps the level to the term pregancy
Changes of blood system
Volume: increased (30-45% ) begain 6- 8 weeks
and up to the peak at 32-34 weeks
increased about 1500ml including
plasma 1000ml and red cell 500ml
Changes of blood component
Red cell: reticulocyte increased
red cell decreased 3.6×1012(4.2×1012)
Hb decreased 110g/L(130g/L)
WBC: neutrophilic granulocyte increased
lymphocyte mild increased
no change in orther blood cells
Coagulation
Hypercoagulability
Factor ⅱⅴⅶ ⅷ Ⅸ ⅹ increased
ESR increased significantly upto 100mm/h
Plasma protein
albumin decreased
THANKS FOR YOUR ATTENTION
Teng Yincheng
M.D., Ph.D., Professor
Dep. of Obstet. & Gynecol.
Renji Hospital Affiliated to SJTU School of Medicine