1. FETAL MEMBRANES AND PLACENTA BY
PROF MASOOD AHMED
MBBS, MPHIL PHD

2. Relative Size of Human Conceptus

3. Implantation of the Blastocyst

4. Implantation of the Blastocyst

5. FETAL MEMBRANES REFRESH FEW TERMS
DECIDUA BASALIS, CAPULARIS AND PARIETALIS
VILLI FORMATION
CYTOTRPHOBLASTIC SHELL FORMATION
CHORIONIC MEMBRANE PARTS
CHORION FURONDOSUM AND CHORION LAEVE
AMNIOCHORIONIC MEMBRANE

9. Embryonic Membranes
Amnion – Epiblast cells form a transparent membrane filled with amniotic fluid
Provides a buoyant environment that protects the embryo
Helps maintain a constant homeostatic temperature
Amniotic fluid comes from maternal blood, and later, fetal urine

10. CYTOTROPHOBLASTIC SHELL FORMATION PLACENTAL BARRIER/ MEMBRANE

11. Embryonic Membranes
Allantois – a small outpocketing at the caudal end of the yolk sac
Structural base for the umbilical cord
Becomes part of the urinary bladder
Chorion – helps form the placenta
Encloses the embryonic body and all other membranes

12. AMNION WITHIN CHORION

13. Placentation The chorion develops fingerlike villi, which:
Become vascularized
Extend to the embryo as umbilical arteries and veins
Lie immersed in maternal blood
Decidua basalis – part of the endometrium that lies between the chorionic villi and the stratum basalis

14. UTERO PLACENTAL CIRCULATION –12TH DAY CIRCULATION
4TH MONTH
CHORION FRONDOSUM AND DECIDUA BASALIS
5TH MONTH
DECIDUAL SEPTA AND COTYLEDON FORMATION
CONTIOUS FLOW IN INTERVILLOUS SPACE

15. PLACENTAL SURFACES Functional type hemochorial FETAL SURFACE
CHORIONIC VESSELLS CONVERGING TOWARDS UMBLICAL CORD
2-ARTERIES AND ONE VEIN
CHORION COVERED BY AMNION
ECCENTRIC ATTACHMENT OF UMBILICAL CORD
MATERNAL SURFACE
15-20 COTYLEDONS
Functional type
hemochorial

17. FULL TERM PLACENTA 15-20% INNER SURFACE COVERED WITH PLACENTA
ALL THE TIME SYNCITIAL SURFACE SEPARATES THE MATERNAL BLOOD
COTYLEDONS- CORE OF ENDOMETRIAL TISSUE COVERED BY SYNSITIUM
15-20 IN NUMBER
SHAPE-DISCOID
SURFACE AREA 15-20cm
THICKNESS-3cm
WEIGHT gms

18. Placentation

19. Placenta DECREASE EXCHANGE BY INCREASE FIBROUS TISSUE IN VILLI
MATERNAL ENDOMETRIALSPIRAL ARTERIES SUPPLYING VILLI
A TOTAL 150 ML BLOOD IN PLACENTAL CIRCULATION
REPL;ENISHES 3-4 TIMES / MINUTE
PLACENTAL BARRIER
SEPARATES MATERNAL AND FETAL BLOOD
COMPRISED OF
ENDOTHELIAL LINING OF VILLI CAPPILARIES
C.T IN VILLI
TROPHOBLASTIC LAYER
CYTO TROPHOBLAST LAYER
4TH MONTHS ONWARD
INCREASED EXCHANGE BY
C.T AND TROPHOBLAST LAYER DISAPPEAR
CLOSE TO END OF PREGNANCY
DECREASE EXCHANGE BY
INCREASE FIBROUS TISSUE IN VILLI
FIBRINOID DEPOSIT ON SURFACE OF VILLI
OBLITERATION OF SMALL CAPPILARIES

20. Variations of placenta
Normally---hemochorial and eccenteric
Variations
velamentous –when umblical vessels divide before and branches come to placenta
Marginal- when umblical vessels join placenta at margin
Succenturiate- when additional small plcental lobe is present or separate small placenta is present
accreta- when placental reaches up to basal layer of endometrium
Increta- when placental infiltrates in the myometrium
Percreta- when placenta infiltrates up to connective tissue and crosses the muscule layer

21. AMNIOTIC FLUID Polyhydroamnios Oligohydroamnios
SYNTHESIZED BY
CLEAR WATERY FLUID
MAINLY BY
MATERNAL CIRCULATION
PARTLY BY AMNIOCYTES
30-ML—10TH WEEK
350 ML—20TH WEEK
ML---37TH WEEK
REPLACED /3-4 HRS
5TH MONTH ONWARD
SWALLOWING
AND ADDITION OF URIN
FUNCTIONS
ABSORBS JOLTS
ALLOW FETAL MOVEMENTS
HORMONE PRODUCTION
AVOIDS ADHERENCE
Polyhydroamnios
Amount of amniotic fluid
more than 1500 ml eg
Esophageal atresi, anencephaly
Oligohydroamnios
less than 400 ml eg
Renal agenesis

22. Membranes in twins DIZYGOTIC OR FRATERNAL twins
Separate amniotic and chorionic membranes and placenta
May be different sex, blood groups, features

23. Monozygotic twins
If twins form by the division of zygot at two cell stage with the formation of two separate blastocyst
Two Separate amniotic and chorionic membranes and placenta
Features,Sex and blood groups same

24. If twins form by the division of inner cell mass in blastocyst
Two Separate amniotic cavities
Common chorionic membranes and placenta
Features, Sex and blood groups same

25. If twins form by the late division of inner cell mass in blastocyst or by division of bilaminar germ disc
Common amniotic, chorionic membranes and placenta
Features, Sex and blood groups same