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

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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
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