Download ovulation...fertilization …implantation

Dr.Sharifa Al-sibiani
OVULATION...FERTILIZATION …IMPLANTATION
& PLACENTA
DR.SHARIFA AL- SIBIANI
Part One Of Lecture :
Ovulation,Fertilization & Implation
(first week of development)
INTRODUCTION (Embriology & 0ogenesis)
AT 3RD WEEK OF DEVELOPMENT:
Primordial Germ Cells from the Yolk Sac.
Start migration
By ameboid Movement
AT THE END OF 4TH & BEGNING OF 5TH WEEK
They arrive Primitive Gonads { Ovary :Cortex , Testes : Medulla }
Primaordial cells
Mitotic division
Oogonia (grouped in Cluters)
1st Meiotie Prophase
Oocytes
th
5 month of gestation : Max no. Oogonia (7million)
7th Month of gestation:
 All Oogonia are Transformed .Birth into I oocytse
 Majority of Oogonia have Degenerate
1
Dr.Sharifa Al-sibiani
AT BRITH (Postnatal Maturation)
 Oogonia are absent.
 Each of Oocyte is surrounded by single layer of Follicular cells
( Primordial Follicle)
 All 1Oocytes have finished the prophase of 1st Meiotic division &
enter the Dictyotene stage (resting phase between prophase &
Metaphase.
 About 2. Millions 1ry Oocytes in both ovaries.
AT PUBERTY
With the onst of Puberty ,with each ovarian cycle(*Regular cycle GnRH, FHS , LH)
*5-12 Primiordial Follicles begin Grow
under influence of FHS & only one reaches full maturity
As Folliculo – Genesis Progress.
 Fluid & space appear between the Follicular cell (Granulosa cells)
These Fluid Spaces Coalse together to form a large Fluid Cavity called Antrum
1ry Follicle

2ry Follicle
At same time Ovarian Stroma cells Differntiate forming Theca cell
1. Theca interna
2. Theca externa
Mature Graafrian Follicle ( Full Grown Follicule =2-3 um)
A Mature Follicle is Composed of (from out side to inside)
1.
2.
3.
4.
Theca cells
Membrana granulosa
Ovum
Liquor Follicule
2
Dr.Sharifa Al-sibiani
IN Mature Graafian Follicule
Shortly before Ovaluation *1 Oocyte
resume the Metaphase of its first Meiotic division
two daughter cells
First Polar
2ry Oocyte
2ry Oocyte enters 2nd Meiotic division
at the moment the 2ry Oocyte shows the Spindle Ovaluation occurs
Completion of 2nd Meiotic division of the 2ry Oocyte & Casting off second Polar body
doesn’t Occur untill after Fertilization.
 When ?
 Time

Around Mid Cycle
2 min
How?
- Prostaglandin Synthesis by Granuolosa Cells increase Prior to Ovulation .it may Play
a roll in the release of
Collagenase
Lysosamal enz
Plasminogen
*Indomethazin Block Ovulation
- Ovulation is direct result of LH Surge ,as it Occurs some 12 hrs. after the peak of LH
values (HCG administered during the late Follicular period is followed by Ovulation after
remarkable Constant 32 hrs)
3
Dr.Sharifa Al-sibiani
High points
Initiation of Follicular activity doesn’t depend on Gonadotrophins
Follicular development occur during
1. Fetal life
2. Childhood
3. Pregnancy
4. Lactation
Follicles begin development in the same sequence as their arrival as Germ cells in the
embryonic Ovary (first in first out theory)
Function
 Secretion of Progesteron & Estrogen mainly Progesteron( Secretory phase)
 Fates
Ovum
Fertilized
Not Fertilized
10-12 days after
Ovulation
CL of Pregnanc
till placenta start
function
Degeneration
Cl of menses
Corpus
Albicans.
4
Dr.Sharifa Al-sibiani
 Ovary
Tube
1. Sweeping Rhythmie Movement of Finbriae
2. External or Internal Migration

Tube
Uterine Cavity
1.Contraction of Muscular wall of tube
2. Rhythmical action of Cilia
Oocyte to site of Fertilization (Uterine tube Ampulla) 25 minutes






Normal semen analysis
Volume 2-5 ml
Count at least 20 million / ml
Motillity 50%
Abn. forms < 15%
Ph 7.5
Liquefation 30 minutes
Tail motility
 Early progress (cx. canal)
 Transit through zona Pellucida
1. Watery cx.secretion
2. Coagulum.
3. CX. Mucus, PH of Vagiana,
Glycoprotein Network
4. Alkalinity of Seminal Fluid
5. Hydrolytie enzymes
6. Low Grade Uterine Contration
5
Dr.Sharifa Al-sibiani
Q1. How long is take a Sperm to reach the Fertilization site?
about 5 minutes
Q2. How many sperms . reach the fertilization site?
only 300 – 500 sperms
one only enters the Ovum
Sperms up on arrival to female Genital tract are not capable of
Fertilization the Oocyte.
For doing so, sperms must under go
1. Capacitation
2. Acrosome reaction


Lasts for about 7 hours
Include:




1. Removal of Glycoprotein Coat
2. Depolarization
Usually occur in Uterus & Tubes
Done by Follicular Fluid
No morphological changes
Permit Acrosomie reaction to occur.
 Immediately near Oocyte , under influence of a substance released
from corona radiata
 Consists of structural changes:
1. Swelling of acrosome
2. mutliple points fusion between plasma mem.& outer mem of
acrosome
The released substance:
1. Hyaluronidase penetration of corona radiata
2. Trypsin like s(acrocin ) of zona lysin
digestion & penetration of zp.
6
Dr.Sharifa Al-sibiani
Fertilization
Definition:- The process by which male & female Gametes fuse
together.
 Site: Ampulla of the tube.
 Germ cell viability:Ova 12-24 hours
Sperm 24-48 hours.
 Phases:1. Penetration of Corona Pellucida
2. Penetration of zona Pellucida
3. Fusion of Oocyte & Sperm cell Membrane.
As soon as Sperm has entered the Oocyte , the Ovum responds in 3 different
ways :
1. fast block
2. Late block
3. Metabolic activation of Oocyte.
4. Resumption of 2nd Meiotie Oocyte finishes its 2nd Meiotic division
immediately after the entry of Sperm (Female Pronucleus),
5. Sperm nucleus become Swollen & tail is detached
(Male Pronucleus)
1. Restoration of Diploid no. of Chromosome.
2. Determination of sex of the new individual
3. Intiation of Cleavage.
7
Dr.Sharifa Al-sibiani
Defination :- A series of rapid Mitotic cell division .
 frist cleavage take place in Ampulla. within 30 hrs of Fertilization .
then , every 12 hours synchronous.
 The daughter cells formed by cleavage are called blastomeres.
 Begins at 12- 16 cells stage.
 Ends when the blastomeres. cells stage is formed Morula.
Outer cell mass
Inner cell mass
Trophoblast
Embryo proper
 The blastocyst lies free in uterine cavity for about two days
 Stage of implantation
 Total size of blastocys = Size of 2ry
8
Dr.Sharifa Al-sibiani
TIME :6days after fertilization
SITE : endometrium of upper segment of uterine body anteior or
posteior
needs :Appropriate estrogen & progesterone
Endometrium in early secretory phase .
STAGES:
1. Apposition
2. Adhesion
3. Penetration
As soon as trophoblast attaches to endometrial epth. it prolififerate rapidly
&differentiates into:1. Inner Cytotrophablast
2. Outer syncytiotrophololast (synctium)
 Apposition : Polar cells , under influence or trypsine endom
mitosis pinpods, withdraw fluid from the lumen by pincytosis
 Adhesion :- Microvilli disappear.
production of sickly glycoprotien
 Penetration :- By contraction of microfilament in trophoblast
blastocyst to migrate between the endometrtial cells.
9
Dr.Sharifa Al-sibiani
Part two Of Lecture
The Placenta = A Circular cake (Latin word)
Defination :- Any intimate apposition or Fusion of Fetal organs to
material tissue for the purpose of Physiocal exchange
The Basic Parenchyma of all Placentas is Trophoblast
Human Placenta :-Describe as Discoid,Decoid, Deciduate, Hemochorial
Chorio all Antoic Placenta.
By Beginning of the 2nd Month
 The trophoblast is Characterized by a greater no of 2nd or 3rd Villi which
give it a radial appearance.
 The Villi are Anchord in the Mesoderm of the Chorinonic Plate &
attached Peripherity to the Maternal Decidua by the outer Cyto
trophblast shell.
 The surface of the Villi is formed by syncytrium (resting an a large of
cyto trophoblastic sells which in trun cover a core of Vascular
Mesodium)
10
Dr.Sharifa Al-sibiani
Beginning Of the 4th Month
 The Cyto trophoblastic cells as well as some of C.T Cells
Disappear.
 The Syncytium & the Endotrellial Wall Of the B.V are
then the only Layers in Seprate the Material & Fetal
Circulation.
 Decidua form a No. of Septa (Decidual)
1. Septa which Project into the intervillous space but don’t
reach the chorionic plat.
2. As the result of these septum formation the placenta is
divided into a number of compartments of cotyledons .
(since the decidua septa don’t reach the chorionic plate
contact the intervillous space in the various cotyleclous is
maintained)
By the beginning of the 4th month the placenta has 2
components:
1.Fetal Protion :-Formed By chorion Frondosum.
(4/5 of total Placenta)
2. Maternal Portion : Formed By Decidua basalis
(1/5 of total Placenta)
11
Dr.Sharifa Al-sibiani
 A blue & Rounded, Meaty Discoid organ
( diameter of 15-25 cm)
 2-4cm thick.
 Wt.=400-600 Gram (1/6 of Normal weight of the newborn)
 Maternal surface = 15-20 cotyledons (slight Building, cover
by a thin layer of decidua basalis.
 Grooves between the cotlyledons are formal by the decidual
septia
Velamentous insection :- Cord insert into the chorionic Mb.
Outside the placenta
1. Exchange of Gases ( O2, Co2 , CO1 )
 Simple Diffusion
 At term the Fetus Extract 20-30 ml of oxygen / minute
from the mother circulation
.
2. transmission of maternal Antibodies
By Pinoceplosis of syneytio trophoblastes
Eg: Rubella, Small Pox , Diphtheria & other Rh/ in
Compatibility
3. Hormone Production :- Progesteron , Estradiol, HPL
4. Infectious agent transfer such as rubella virus.
5. Drugs transfer
12
Dr.Sharifa Al-sibiani
 Receive Blood Through 80-100 Sprial arteries
 Spiral artery ( with narrow lumen ) →↑ Bp →
When entering the intervillous space → bath the villous
free with Oxygenated blood →↑ BP Blood flows back from the
choronic plate towards the decidua → enters the endometrial
vieins→ Drains back into the material circulations.
 Intervillous space of the full – growth placenta contain
approx 150 cc of blood which replenished about 34minutes.
 Chorionic villi surface area =4.14M2
GOOD LUCK
13