Embryo 1b

embryonic sac lies in the uterine lumen or cavity

Embryonic sac lies in a fold or pocket of the uterin wall

embryonic sac penetrates and is embedded into the uterine wall

Nutrition from secretion of uterine gland

Nutrition frm maternal circulation

Composite structure formed btw fetal membranes and maternal tissue for the purpose of physiological exchange

• Fetal membranes involved
• Shape of placenta
• Branching of chorionic villi
• Loss of maternal Tissue at parturition
• Histological Layers

yolk sac and chorion

chorionic villi uniformly distributed over sac

tufts of chorionic villi attach to endometrial caruncles -> PLACETOME

chorionic villi form a band around sac

Chorionic villi form 1-2 discoid shaped areas

simple branching of chorionic villi

complicated/anastomotic branching of villi

little loss of maternal tissue

extensiv loss of maternal tissue d/t complicated interlocking of fetal/maternal tissue

Chorionic epithelium in contact with unterine epithelium (6 layers)

Chorionic Epithelium is in contact with unterine CT (5 layers)

Chorionic Epithelium is in contact with endothelium of uterine BV (4 layers)

Chorionic Epithelium is in contact with uterine blood (3 layers)