039 Placentation Flashcards
Which element of the trophoblast produces hCG, and what does hCG levels represent?
syncytiotrophoblast - represents the differentiation (peaks at around 8 weaks)
How do you distinguish syncytiotrophoblast from cytotrophoblasts?
syncytiotrophoblast will have no mitotic activity
Describe the 3 stages of chorionic villi formation
- primary villi: central mass of ctotrophoblast with thick syncytiotrophoblast as outpouching
- secondary villi: villi acquiring central mesenchymal core from extraembryonic mesoderm. Villi is branched
- Tertiary villi: appearance of extra embryonic vessesl within the mesenchymal cores.
What does the villous core contain?
mesenchymal cells, collagen firbes, hofbauer cells (macrophages)
What prevents anti-foetal antibodies from entering?
Hofbauer cells phagocytose anti foetal antibodies.
Why is it important for external layer of cytotrophoblast to be sealed until 12 weeks?
Prevent oxygen from entering because free radicles from maternal blood might cause miscarriage as foetus doesnt have enzymatic defences for free radical.
What is used as a diagnostic tool for ectopic pregnancy?
The prescence of yolk sac
When does the yolk sac dissapear?
When amniotic and chorionic cavities burst and fuse into one at 12 weeks.
What is the difference between desidual basalis, desidual pariatalis, and desidual capsilaris?
desidual basalis - forms the placenta
desidual pariatalis - around the sides
desidual capsilaris - at the luminal side of embryo
all a part of the endometrium.
What is the difference between chorion lave and chorion frondosum?
chorion lavae –> contaicts the decidua capsilaris
chorion frondosom –> contacts the desidua basalis
What two components is the placenta formed by?
desidua basalis and chorion frondosum
What are cotyledons?
When septae project into intervillous space but dont reach chorionic plate, separating the decidua basalis of the placenta, formed in month 4-5/
