Developmental structures Flashcards
What is the purpose of the placenta?
Primary site of nutrient and gas exchange between mother and fetus.
What is the fetal component of the placenta?
Cytotrophoblast and Syncytiotrophoblast
What is the cytotrophoblast?
Fetal component. Inner layer of chorionic villi. Cytotrophoblast makes Cells.
What is the Syncytiotrophoblast?
Outer layer of chorionic villi. Secretes hCG, which stimulates corpus luteum to secrete progesterone during first trimester.
- LACKS MHC-I expression! Lower chance of attack by maternal immune system.
What is the decidua basalis?
Maternal componenent of the placenta. Derived from endometrium. Maternal blood in lacunae.
What are the contents of the umbilical cord?
1 umbilical arteries, 1 umbilical vein.
What are the contents and pathway of the umbilical arteries?
Deoxygenated blood from fetal internal iliacs to placenta.
What are the contents and pathway of the umbilical vein?
Supplies oxygenated blood from placenta to fetus - drains into IVC via liver or ductus venosus.
Where are the umbilical arteries and vein derived from?
allantois
What is the cushioning around the vessels in the umbilical cord?
“Wharton jelly”
Where are the umbilical arteries and vein derived from?
Allantois
When does the yolk sac form the allantois?
3rd week
What is the allantois when it forms?
Outpouching of yolk sac connect to the urogenital sinus.
What does the allantois become?
When urogential sinus forms bladder, allantois is called the urachus, a duct between fetal bladder and yolk sac.
If there’s urine discharge from the umbilicus at birth, what happened?
Patent urachus
What is a urachal cyst? What complications are associated with it?
Partial failure of urachus to obliterate leaving fluid-filled cavity lined w/ uroepithelium, between umbilicus and bladder. Can lead to infection, adenocarcinoma.
What is a vesicourachal diverticulum?
Slight faliure of proximal urachus to obliterate - outpouching of bladder, usually asx.
What does the vitelline duct connect? What else is it called?
Yolk sac to midgut lumen. Omphalomesenteric duct.
What causes meconium discharge from umbilicus?
Failure of vitelline duct closure. Vitelline fistula.
What does partial failure of vitelline duct to close cause?
Meckel’s diverticulum. Partial closure of vitelline duct with patent portion attached to ileum. True diverticulum. May have heterotopic gastric/pancreatic tissue.
