187- Fertilization/implantation

Question 1

What protein can cross the placenta?

Answer 1

IgG

Question 2

What is the fetal component of the placenta called? what is it made of?

What is the maternal component?

What is the intervillous space?

Answer 2

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

Question 3

what are the membranes that surround the fetus

Answer 3

Amnion, chorion, parietal decidua

Question 4

what does the umbilical cord contain?

What are the vessels derived from

Answer 4

2 umbilical arteries (deox), 1 umbilical vein (ox), allantoic duct, wharton’s jelly.

allantois

Question 5

What happens to the maternal spiral arteries in the decidua?

What if that doesn’t happen?

Answer 5

invaded and remodeled by extra-villous trophoblast to become a low-pressure, unreactive system.

Predisposition to preeclampsia

Question 6

What is the first differentiation of the cells? What is the “switch” that determines differentiation?

Answer 6

embryonic stem cells become trophectoderm when there is DECREASED Oct4 and INCREASED Cdx2. Otherwise they become part of inner cell mass

Question 7

What are the first stages of the egg after fertilization? What is the timeline and location for each?

Answer 7

Fertilized in the ampulla. Two cell stage (30 hours). Morula containing 12-16 blastomeres (3 days). Early blastocyst enters uterus (5-9 days).

Question 8

how does the blastocyst attach? Where does it normally attach?

Answer 8

L selectin. Anterior or posterior wall

Question 9

What happens after implantation?

Answer 9

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)

Question 10

What tissue forms the vessels? difference b/w vasculogenesis and angiogenesis?

Answer 10

mesodermic mesenchyme (arrises inside the cytotrophoblast). New vessel development vs new branching

Question 11

What accounts for the increased size of the baby relative to the placenta?

Answer 11

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