2nd week of development Flashcards
What does the trophoblast become?
cytotrophoblast
syncytiotrophoblast
What does the embryoblast become?
epiblast
hypoblast
(together they are the bilaminar germ disc)
What does the extraembryonic mesoderm split into?
splanchnopleure
somatopleure
What two cavities form?
amniotic cavity
Yolk sac cavity
Where are the hypoblast and epiblast?
hypoblast is near the blastocyst and the epiblast is near the amniotic cavity
what is the fibrin coagulum?
what closes off the penetration defect in the endometrium
What happens in the lacunar stage?
vacuoles appear at the embryonic pole in the syncytium and form large lacunae;
the hypoblast cells form a membrane called the exocoelomic membrane
exocoelomic membrane + hypoblast=
exocoelomic cavity/ prmitive yolk sac
What is the extraembryonic mesoderm?
It is loose connective tissue that develops between the exocoelomic cavity and the cytotrophoblast
(cytotrophoblast side = somatopleuric and yolk sac side = splanchnopleuric)
How is uteroplacental circulation established?
Lacunae hook up with sinusoids and maternal blood enters the lacunar system
What is the chorionic cavity?
the large cells that develop in the extraembryonic mesoderm and join together
What is the decidua reaction?
cells at the site of implantation become filled with glycogen and lipids and it eventually spreads to the whole endometrium
how is the secondary yolk sac formed?
a proliferation of the hypoblast which may produce exocoelomic cysts
where is the only place that the chorionic plate crossses the extraembryonic mesoderm after the formation of the chorionic cavity?
connecting stalk (future umbilical cord)
What does the mother produce that keeps the fetus from being rejected immunologically?
immunosuppressive cytokines unusualy major histocompatibility complex class IB
