Downing: Placental Histology Flashcards
required for for endometrial invasion by the placenta
secretory phase
trophoblast proliferation (lacunar formation) >
uterine epithelium regneration>
decidual rxn
Endometrial invasion of the placenta
Components of the chorionic villi
extraembryonic mesoderm
cytotrophoblast
syncytiotrophoblast
1 villi
trophoblast only, no extraembryonic mesoderm yet
2 villi
mesodermal ingrowths into villous core
branding occurs
villi w/ cytotrophoblastic shell that invade through the syncytiotrophoblast and have direct contact w/ decidual cells
anchoring villi
villus that have differentiation of blood vessels in villus core and eventual anastamosis of villar blood vessels w/ fetal circulation
3 villus
where is the decidua basalis formed
between conceptus and myometrium
this constitutes the MATERNAL portion of hte placenta and is the site of decidual rxna nd most extensive villar invasion
decidua basalis
between the conceptus and uterine lumen
decidua capsularis
decidua parietalis
remainder of endometrium
Cotyledons
placenta divided into 15-30 lobules by septae from decidua basalis (contain 3 villi branches)
Fetal placenta circulation
umbilical a> chorionic a> villar capillaries> chorionic veins> umbilical veins
Maternal placental circulation
spiral arteries>
intervilous space>
endometrial veins
How often is blood in intervillous spaces replenished?
3-4x/min
first trimester placental barrier
syncytiotrophoblast cytotrophoblast basal lamina of trophoblast fetal CT basal lamina of fetal capillaries fetal endothelium
What happens to the first trimester barrier after 20 weeks?
cytotrophoblast disappears and CT thins and barrier is reduced to:
syncytiotrophoblast
basal laminae
fetal capillaries
what is transferred in the placenta
gases nutrients hormones IgG fetal RBC (RH incompat) urea drugs viruses (NO bacteria)
origin of most placental hormones
syncytiotrophoblast
LH like glyucoprotein that MAINTAINS the CL and measure ment is used to detect pregnancy
hCG
related to HGH, stimualtes general growth and is lactogenic
Human placental lactogen
synthesized by decidual cells
PRL
PG
Relaxin
helps soften cervix and pelvic ligaments
relaxin
