Embryo 0502FA Flashcards
cytotrophoblast
inner layer of chorionic villi.
makes cells.
syncytiotrophoblast
outer layer of chorionic villi.
secretes hCG to stimulate corpus luteum during first tri.
decidua basalis
derived from endometrium.
maternal bld in lacunae (between villi).
umb arteries
TWO.
return deoxy bld from fetal internal iliac aa. to placenta.
umb vein
ONE.
carry oxy bld from placenta to fetus.
drain into IVC.
urachus
3rd wk
yolk sac forms allantois, which extends into urogenital sinus. allantois becomes urachus (between bladder and yolk sac)
patent urachus
failure of urachus to obliterate.
urin discharge from umbilicus.
vesicourachal diverticulum
failure of urachus to obliterate.
outpouching of bladder.
vitelline duct
7th wk
obliteration of vitelline duct which connects yolk sac to midgut lumen
vitelline fistula
failure of duct to close.
meconium discharge from umbilicus.
Meckel’s diverticulum
partial closure of vitelline duct, with patent portion attached to ILEUM - may have ectopic gastric mucosa w/ melena, periumbilical pain.
sites of fetal erythropoiesis
Yolk sac: 3-10 wk
Liver: 6 wk-birth
Spleen: 15-30 wk
Bone marrow: 22 wk-adult
“Young Liver Synthesizes Blood”
fetal Hb
alpha 2, gamma 2
adult Hb
alpha 2, beta 2
fetal shunts
- ductus venosus: umb vein into IVC (bypass hepatic circ)
- foramen ovale: oxy bld from IVC through FO, pumped out aorta to head and body
- ductus arteriosus: DEoxy bld from SVC expelled into pulmo artery then DA to lower body then umb aa. to placenta
