8.1 Placenta Flashcards
when does the placenta begin to develop?
2nd week
is the placenta a fatal membrane?
yes, a specialised one
what’s produced by the syncytiotrophoblast? function?
hCG
maintains corpus luteum and steroid hormones for a viable pregnancy
which cell mass develops into the placenta?
outer
relationship of embryo+syncytiotrophoblast to maternal endometrium at end of implantation
integral
why does the yolk sac disappear?
primitive gut development pinches it off
why does the amniotic cavity enlarge?
fetus enlarges
formation of amniochorionic membrane
amniotic and chorionic membranes fuse
‘waters breaking’
break of amniochorionic membrane releasing amniotic fluid, signals start of labour
why don’t the maternal blood and feral blood circulations never mix?
separate genetics
why do the metabolic needs of the foetus increase?
fatal brain grows so needs more E (glucose)
decidua function
manages depth of invasion of implantation, balanced against aggression from enzymes released from syncytiotrophoblast
why can ecptoic pregnancies implant deeply?
no decidua so cant control depth of invasion
cotyledons
functional units containing chorionic villi (allow transport)
why do chorionic villi become thinner by end of pregnancy? how do they thin?
metabolic requirements of fetus increase
lose most of cut-trophoblast layer (small amount left is for stem cells)
