Extra-embryonic membrane and placentation

陳建榮http://web.nchu.edu.tw/~chenjr/index.htm

胚外膜 (extraembryonic membrane):1. 絨毛膜 (chorion)2. 羊膜 (amnion)3. 卵黃囊 (yolk sac)4. 尿囊 (allantois)

Placenta 胎盤

Fetomaternal organFetomaternal organFetal portionFetal portion: villus chorion of chorionic sac

Maternal portion:Maternal portion:

the functional layer of endometriumEndomatrial stromal cell Decidual cell 蛻膜細胞

(decidual reaction) decidua basalis

Decidua: decidua basalis 基蛻膜 decidua capsularis 囊蛻膜 decidua parietalis 壁蛻膜

Villi:-primary chorionic villi-secondary chorionic villi-tertiary chorionic villi or stem villi

Cytotrophoblastic shell 細胞滋養層殼

絨毛膜板

Cytotrophoblastic shell 細胞滋養層殼

胎盤膜 (placental membrane) 10 weeks

full term

Erythroblastosis fetalis 胎性母紅血球增多症

胎盤膜 (placental membrane) -合體滋養層-細胞滋養層-絨毛的結締組織-胎兒微血管內皮

Functions of PlacentaFunctions of Placenta

-代謝 (metabolism)-synthesis glycogen, cholesterol, fatty acids…

-運送氣體和營養素-營養 (nutrition)-呼吸 (respiratory)-排泄 (excrection)

-激素製造 (hormone production)

Placental abnormalities-Placenta percreta 植入性胎盤-Placenta accreta 胎盤黏連-Placenta previa 前置胎盤

Placental abnormalities

Uterine growth during pregnancy

Fetal membrane: amnion, yolk sac

3 week

4 week

10 wks

20 wksAmniotic fluid

Amnion 羊膜

Amniotic fluid :-10 週— 30ml; 20 週— 350ml; 37 週— 800-1000ml-Sources ：

-amniotic cells, secretion of respiratory tract, maternal fluid, urine-Circulation ：

-未皮質化之皮膚-消化道吞食或呼吸道吸入，吸收後進入血流，再經胎盤交換

-Function ： - 平衡或對稱生長 - 提供自由運動 - 傳染疾病的壁障 (barrier) - 防止黏連 - 吸收震動 - 維持恆溫

Amniotic cavity

Allantosis and yolk sac3 wks 9 wks

3 month Adult

Yolk sac 卵黃囊 :-Nutrition (2nd~3rd week)-Vasculogenesis and angiogenesis-Foregut, midgut and hindgut-Primordial germ cell

Allantois 尿囊 -Derived from yolk sac-Vasculogenesis umbilical a. and v.-Uninary bladder-Urachus median umbilical lig.

Umbilical cord:-Connecting stalk, amnion -30~90cm-1 umbilical v. and 2 umbilical a.-False knots and true knots

False knot

Parturition (labor) 分娩 :1. Dilation stage 擴張期2. Expulsion stage 排出期3. Placental stage 胎盤期4. Recovery stage 恢復期

Parturition: 1. Dilation stage: 7-12 hrs

Oxytocin

陣痛

子宮開始收縮 ( 真陣痛 )

a. 子宮頸口變薄

b. 擴張子宮頸口→ 10 公分

Parturition: 2. Expulsion stage: 20’-50’

Parturition: 3. Placental stage: 15’

4. Recovery stage > 2hrs

胎頭過大、臀產式、胎兒窘迫

胎盤早期剝離、前置胎盤、臍帶脫出

胞衣、胎衣（紫河車）

Dizygotic twins: separate

Dizygotic twins: fused

Monozygotic twins

Dizygotic (DZ) twins Monozygotic (MZ) twins (65%)

Zygote 2 1(2 embryoblasts)

Fetal 2 amnions 2 amnionsmembrane 2 chorions or fused 1 chorion

2 placentas or fused 1 placenta

Sex various same sex

Genotype different sameIncidence racial difference the same in populationRate increase with mother’s age independent with mother’s age

Multiple pregnanciesMultiple pregnancies

Fetal membrane of bird

Yolk sac

Allantois Amnion

Chorion

Classification Based on Placental Shape and Contact Points-Diffuse placenta 擴散型胎盤 : Seen in horses and pigs.-Cotyledonary placenta 子葉型胎盤 : This type of placentation is observed in ruminants.-Zonary placenta 帶狀胎盤 : Seen in carnivores like dogs and cats, seals, bears, and elephants.-Discoid placenta 盤狀胎盤 : Seen in primates and rodents.

Placentation in Horses Diffuse placenta 擴散胎盤

Placentation in Horses Diffuse placenta 擴散胎盤

Cotyledonary placenta 子葉型胎盤

Placentation in Ruminants

Placentation in Ruminants

Placentation in Dogs and Cats Zonary placenta 帶狀型胎盤

Placentation in Dogs and Cats

Discoid placenta 盤狀胎盤

Human

Rodent

胎盤膜 (placental membrane)

Type of Placenta

Maternal Layers Retained

ExamplesEndometrialEpithelium

ConnectiveTissue

UterineEndothelium

Epitheliochorial上皮絨毛膜型 + + +

Horses, swine, ruminants

Endotheliochorial內皮絨毛膜型 - - + Dogs, cats

Hemochorial血液絨毛膜 - - - Humans, rodents

Epitheliochorial 上皮絨毛膜型

Summary of Species Differences in Placental

Architecture

Type of Placenta Common Examples

Diffuse, epitheliochorial擴散型胎盤 , 上皮絨毛膜型 Horses and pigs

Cotyledonary, epitheliochorial子葉型胎盤 , 上皮絨毛膜型

Ruminants (cattle, sheep, goats, deer)

Zonary, endotheliochorial帶狀胎盤 , 內皮絨毛膜型 Carnivores (dog, cat, ferret)

Discoid, hemochorial盤狀胎盤 , 血液絨毛膜

Humans, apes, monkeys and rodents