Good Afternoon Ev

eryone

Fetal membrane and placenta

1. Fetal membranechorion

yolk sac

amnion

allantois

umbilical cord

Ⅴ.

ChorionFormation Secondary stem villi chorion villi chorionic plate

Structure of villiPrimary stem villi

syncytiotrophoblast cytotrophoblast extraembryonic mesodermwith blood vessels

Secondary stem villi: syncytiotrophoblast

cytotrophoblast extraembryonic mesoderm

固有胎盘绒毛

definitive placental villi

tertiary stem villi:

Cytotrophoblastic cell column

cytotrophoblastic shell

intervillous space

free villi anchoring villous

Evolution of chorion

Chorion leave

Chorion frondosum

Hydatidiform mole chorioepithelioma

Abnormal development

Yolk sacFormation and evolutionvitelline stalk vitelline duct

Meckel’s diverticulum

Umbilical fistula

Abnormal Development

Significance

blood island 血岛 earlist hematopoietic organ

producing primordial germ cell

AmnionFormation and evolution :

amniotic fluid

Function

fetal free movement

serves as a protective cushion

① preventing the adhesion of embryo②absorbing shakes

③dilating the cervical canal lubricating the delivery tract

Normal volumeAbnormal volume Oligohydramnios kidney hypoplasia urethra atresiaPolyhydramnios anencephaly esophageal atresia

Allantois Formation and evolution: urachus median umbilical ligament

Significance allantoic arteries umbilical A allantoic veins umbilical V

Abnormal development Urachal fistula urachal diverticulum urachal cyst

umbilical cord

Formation

Structure:Amniotic membrane

retrograde allantois

retrograde yolk sac

body stalk(connective tissue)

umbilical A umbilical V

Normal Length

40 ～ 60cm D: 2cm

Intervillous space Decidual septum

Cytotrophoblast shell

Spiral artery

Decidua basalis

Chorion laeveChorion frondosum

Encircling neckLong cord >80cm

Abnormalities Related to Umbilical Cord

Encircling leg

Short cord: <35cm may result in premature pull and separation of

placenta causing severe bleeding during birth

Umbilical Cavity

umbilical hernia

2.Placenta Form:

maternal surface (cotyledon)

Placenta: fetal surfacePlacenta: fetal surface

structure

Maternal portion: decidua basalis

Fetal portion: chorion frondosum

blood poolplacental septum

Intervillous space Decidual septum

Cytotrophoblast shell

Spiral artery

Decidua basalis

Chorion laeveChorion frondosum

3 layers: basal plate decidua basalis cytotrophoblastic shell

Villi and intervillous space

chorionic plate

Intervillous space

Placenta septum

Free villus

chorionic plate basal plate

Cytotrophoblastic shell

Cytotrophoblastic column

Intervillous space Decidual septum

Cytotrophoblast shell

Spiral artery

Decidua basalis

Chorion laeveChorion frondosum

Blood circulation of the placentaMaternal circulation: coiled A→ intervillous space→ endometrial venules

fetal circulation: umbilical A→capillaries of villus→umbilical V

Placental membrane (barrier)

syncytial trophoblast

cytotrophoblast and its B.Mconnective tissue in the villus B.M and endothelium of capillary

1.Syncytium 2.cytotrophoblast and its B.M3.connective tissue4.B.M and endothelium of capillary

1.Syncytium and its B.M

2. B.M and endothelium of capillary

1.Syncytium2. B.M3. endothelium

1.Syncytium 2.cytotrophoblast 3. B.M of trophoblast4.connective tissue5.B.M of capillary6. endothelium of capillary

Function of the placenta1. exchange of metabolic and gaseous produc

ts Simple diffusion facilitated diffusion active transport pinocytosis2. Production of hormones chorionic gonadotropin estrogen progesterone placental lactogen (chorionic somatomammototropin)3. protection

Ⅵ. Twins , Multiple births and Conjoined twins

1.Twins:

monozygotic twins

dizygotic twins

monozygotic twins

①2 cell stage

② blastocyst stage

③ bilaminar germ disc stage just before the appearance of the primitive streak

dizygotic twins

 2. Multiple Births

1999 年出生 南京四胞胎

冰、清、玉、洁

Multiple births

2008 年 10 月 14 日上午 9 30∶ ，河南省内黄县东庄镇周庄村 27 岁的农村产妇菅晓静，在县妇幼保健医院顺利剖腹生产下三女两男龙凤五胞胎。五胞胎体重分别为 2600 克、 2300 克、 2300 克、 2300 克、 2200 克。

2008 年 10 月 14 日上午 9 30∶ ，河南省内黄县东庄镇周庄村 27 岁的农村产妇菅晓静，在县妇幼保健医院顺利剖腹生产下三女两男龙凤五胞胎。五胞胎体重分别为 2600 克、 2300 克、 2300 克、 2300 克、 2200 克。

Monozygotic ~

Multiple-zygotic ~

mixed ~

Multiple Births

3.Conjoined Twins

胸腹联胎 臀联胎

头联胎寄生胎parasite

联胎种类

Omphalo-thoracopagus

craniopagus

Pygo-pagus

Unsymmetric conjoined twins

Conjoined Twins