187- Fertilization/implantation Flashcards
What protein can cross the placenta?
IgG
What is the fetal component of the placenta called? what is it made of?
What is the maternal component?
What is the intervillous space?
chorionic plate. The villous tree: small fetal vessels covered by inner layer of cytotrophoblast and outer layer of syncitiotrophoblast.
Basal plate. Decidua basalis (modified endometrium with remodeled maternal vessels)
Contains maternal blood surrounding fetal villi
what are the membranes that surround the fetus
Amnion, chorion, parietal decidua
what does the umbilical cord contain?
What are the vessels derived from
2 umbilical arteries (deox), 1 umbilical vein (ox), allantoic duct, wharton’s jelly.
allantois
What happens to the maternal spiral arteries in the decidua?
What if that doesn’t happen?
invaded and remodeled by extra-villous trophoblast to become a low-pressure, unreactive system.
Predisposition to preeclampsia
What is the first differentiation of the cells? What is the “switch” that determines differentiation?
embryonic stem cells become trophectoderm when there is DECREASED Oct4 and INCREASED Cdx2. Otherwise they become part of inner cell mass
What are the first stages of the egg after fertilization? What is the timeline and location for each?
Fertilized in the ampulla. Two cell stage (30 hours). Morula containing 12-16 blastomeres (3 days). Early blastocyst enters uterus (5-9 days).
how does the blastocyst attach? Where does it normally attach?
L selectin. Anterior or posterior wall
What happens after implantation?
The syncitiotrophoblast invades the endometrial stroma before forming lacunae which then eat into the maternal arteries. The lacunae fill with blood and the utero-placental circulation is established (2 weeks)
What tissue forms the vessels? difference b/w vasculogenesis and angiogenesis?
mesodermic mesenchyme (arrises inside the cytotrophoblast). New vessel development vs new branching
What accounts for the increased size of the baby relative to the placenta?
The cytotrophoblast disappears so the diffusion distance isn’t as big from mom to baby. There is increased villous branching which effectively increases the surface area