Implantation 5 Flashcards
Describe the process and importance of remodeling of the maternal spiral arteries.
1
Q
What happens to the maternal spiral arteries in the first tirmester?
A
Invaded by extravillous trophoblast cells top open them up and widen their lumens joining into the sinusoidal intervillous spaces
2
Q
Why must the maternal spiral arteries become eroded and invaded by cytotrophoblasts?
A
- When not pregnant, these vessels are reactive to cytokines, especailly when hypoxic/ischemic
- constrict to divert blood away from the uterus
- During pregnancy, don’t want the fetus to be deprived of oxygen
- Outer smooth muscle is replaced by extravillous trophoblast cells that function as the endothelium during pregnancy
- Effectively diminishes artery reactivity and helps maintain uterine circulation even when hypoxic/ischemic
- Early on, trophoblastic cellular plugs occlude vessels to create hypoxic environment
- thought to facilitate placental growth and differentiation through vasculogenesis and angiogenesis
- plugs broken down when remodeling is complete