FETAL MEMBRANESFETAL MEMBRANES

UMBILICAL CORDUMBILICAL CORD

Initially connecting stalkInitially connecting stalk Blood vessels developBlood vessels develop

Normally 2 arteries, 1 veinNormally 2 arteries, 1 vein Doppler VelocimetryDoppler Velocimetry

With folding shifts ventrallyWith folding shifts ventrally LENGTH: 30-90cm (average 55cm)LENGTH: 30-90cm (average 55cm)

Abnormally long- prolapseAbnormally long- prolapse Abnormally short- premature separationAbnormally short- premature separation

Covered by AmnionCovered by Amnion KnotsKnots

FalseFalse- length of blood vessels more than - length of blood vessels more than umbilical cordumbilical cord

TrueTrue- head passes through loop of cord, - head passes through loop of cord, dangerousdangerous

AmnionAmnion

Initially located cranially Initially located cranially Oval attachmentOval attachment Cavity expands, obliterates chorionic Cavity expands, obliterates chorionic

cavity, lining of umbilical cordcavity, lining of umbilical cord

AMNIOTIC FLUIDAMNIOTIC FLUID

Plays major role in fetal growth and Plays major role in fetal growth and developmentdevelopment

SOURCESSOURCES Initially secreted by amniotic cellsInitially secreted by amniotic cells Maternal tissue, diffusion across Maternal tissue, diffusion across

amniochorionic membraneamniochorionic membrane Diffusion through chorionic plate, from Diffusion through chorionic plate, from

intervillous spaceintervillous space

FETALFETAL Before keratinization, fetal interstitial tissueBefore keratinization, fetal interstitial tissue After that; fetal respiratory tract (300-400ml/ After that; fetal respiratory tract (300-400ml/

day)day) GITGIT By 11By 11thth week: fetal excretory system week: fetal excretory system

(500ml/day)(500ml/day) Volume normally increases slowlyVolume normally increases slowly 30ml- 10 weeks30ml- 10 weeks 350ml- 20 weeks350ml- 20 weeks 700-1000ml– 37 weeks700-1000ml– 37 weeks

COMPOSITIONCOMPOSITION

Aqueous solution with suspended Aqueous solution with suspended materialsmaterials

Epithelial cellsEpithelial cells OrganicOrganic: proteins, enzymes, hormones, : proteins, enzymes, hormones,

pigments, carbohydratespigments, carbohydrates IInorganic:norganic:saltssalts

AMNIOCENTESISAMNIOCENTESIS

AMNIOTIC FLUID EXAMINATIONAMNIOTIC FLUID EXAMINATION Fetal proteins, hormones, enzymes can Fetal proteins, hormones, enzymes can

be studiedbe studied Fetal cells; chromosomal abnormalitiesFetal cells; chromosomal abnormalities Alpha fetoproteins:Alpha fetoproteins:

High- NTDHigh- NTD Low- Trisomy etcLow- Trisomy etc

SIGNIFICANCESIGNIFICANCE

Embryo floats, moves freelyEmbryo floats, moves freely Cushioning effectCushioning effect Barrier to infectionsBarrier to infections Symmetrical growth of fetusSymmetrical growth of fetus Muscular developmentMuscular development Normal fetal lung developmentNormal fetal lung development Prevents adherence of amnion to embryoPrevents adherence of amnion to embryo Controls body temperatureControls body temperature Maintains homeostasisMaintains homeostasis

ABNORMALITIESABNORMALITIES

OLIGOHYDROAMNIOSOLIGOHYDROAMNIOS CausesCauses

Renal agenesisRenal agenesis Obstructive uropathyObstructive uropathy

ComplicationsComplications Pulmonary hypoplasiaPulmonary hypoplasia Facial defectsFacial defects Limb defectsLimb defects

POLYHYDROAMNIOSPOLYHYDROAMNIOS CausesCauses IdiopathicIdiopathic AnencephalyAnencephaly Esophagial atresiaEsophagial atresia

ComplicationsComplications Premature onset of labourPremature onset of labour

YOLK SAC (UMBILICAL YOLK SAC (UMBILICAL VESICLE)VESICLE)

SIGNIFICANCESIGNIFICANCE

Transfer of neutrientsTransfer of neutrients Blood vessels developmentBlood vessels development Endoderm- epithelium of gut, trachea, Endoderm- epithelium of gut, trachea,

lungslungs PGCsPGCs

AllontoisAllontois

MULTIPLE GESTATIONMULTIPLE GESTATION

DIZYGOTICDIZYGOTIC: : 2/32/3rdrd

7-11/10,000 births7-11/10,000 births Simultaneous shedding of two ova, Simultaneous shedding of two ova,

fertilization by two spermsfertilization by two sperms Different genetic make upDifferent genetic make up Resemblance like other siblingsResemblance like other siblings

Implant individuallyImplant individually Each develop own placenta, amnion, chorionic Each develop own placenta, amnion, chorionic

sacssacs

If placents lie closely, may fuseIf placents lie closely, may fuse ERYTHEROCYTE MOSAICISMERYTHEROCYTE MOSAICISM

MONOZYGOTIC TWINSMONOZYGOTIC TWINS

Single ovum is fertilizedSingle ovum is fertilized 3-4/10,000 births3-4/10,000 births From splitting of ovum at different stages of From splitting of ovum at different stages of

developmentdevelopment Earliest at Earliest at two cell stagetwo cell stage Implant separately, separate placentae etcImplant separately, separate placentae etc Resemble dizygotic but same genetic Resemble dizygotic but same genetic

constitutionconstitution

At At early Blastocyst stageearly Blastocyst stage Inner cell mass splits into two within same Inner cell mass splits into two within same

blastocyst cavityblastocyst cavity Common placenta, chorionic cavityCommon placenta, chorionic cavity Separate amniotic cavitySeparate amniotic cavity At At bilaminar germ discbilaminar germ disc Before the appearance of primittive streakBefore the appearance of primittive streak Common placentae, amnion, chorionic cavityCommon placentae, amnion, chorionic cavity Usually blood supply is well balancedUsually blood supply is well balanced May be unbalancedMay be unbalanced Risks are more (one fetus may die) Risks are more (one fetus may die)

TWIN TWIN TRANSFUSION SYNDROMETWIN TWIN TRANSFUSION SYNDROME Shunting of arterial blood from one fetus to Shunting of arterial blood from one fetus to

venous circulation of other. Donor is small, venous circulation of other. Donor is small, pale, anemic while recipient is large and pale, anemic while recipient is large and polycythemicpolycythemic

FETUS PAPYRACEUSFETUS PAPYRACEUS

VANISHING TWINVANISHING TWIN

INCOMPLETE INCOMPLETE SEPARATIONSEPARATION

CONJOINED TWINSCONJOINED TWINS (Siamese)(Siamese) CraniopagusCraniopagus ThoracopagusThoracopagus pyopaguspyopagus