placental development Flashcards
sperm capacitation (3)
removal of epididymal and seminal glycoproteins
- increase membrane permeability to Ca2+
- Ca2+ influx maximizes cAMP, increaes sperm motility
3 main events in fertilization
acrosome reaction
sperm binding ZP3
sperm-egg fusion
acrosome rxn and ZP3
sperm binds ZP3 R on ZP while acrosome reaction takes place to break down ZP
cortical rxns
after first sperm fertilizes the egg cortical granules present in the egg remove oligosacch on ZP3 and partially cleave ZP2
-sperm cannot bing now
what ig superfamily protein on sperm and other protein on egg are required for sperm and egg fusion
Izumo on sperm
CD9 on egg
-mutation in these prevents fusion
fast and slow component of cortical rxn
fast: change in PM potential
slow: cortical rxn
implantation of the blastocyst steps
- blastocyst hatches from ZP
- apposition, adhesion to endometirum: integins on trophoblasts and endometrial cells
- implantation by penetrating trophoblastic cells
decidual reaction
- optimal state of endometrial maturation for implantation
- glycogen stores, very vascular, pinopodes,
- influenced by progesterone
what do syncytiotrophoblastic cells have to get through to invade
what may help hold blastocyst in place
- desmosomes
- pinopodes
endovascular invasion
SCT invades into wall of spiral arteries and replace SM cells, disable ability of artery to constrict which keeps it open and have max amount of blood
spotting or implantation bleeding
bleeding when blastocyst implants
-can be mistaken for a period
what provides an immune protective environment for the development of the embryo
decidua
- secretes immunosuppressive substances such as prostaglandins to inhibit NKC at implantation site
- SCT don’t have MHC II so cannot present to CD4+ cells
primary villi
when sytotrophoblastic cell proliferate and extend into SCT
secondary villi
when XE mesoderm extends into primary villi
tertiary villi
when XE mesoderm differentiate into capillary and blood cells
decidua basalis
fnct part of maternal contribution of placenta
-portion underlying the implantation site
decidua capsularis
portion overlying implanted embryo, seperates it from uterine cavity
decidua parietalis
remainder of endometrium
chorionic villus structure
chore of mesenchymal CT and fetal blod vessels
placental barrier for exchange
1) SCT
2) cytotrophoblast
3) XE mesoderm
4) fetal endothelium
different types of placentas
- bilobed
- circumvallate: umbilical cord on one sise
- succenturinate (extra lobe)
- velamentous cord: placental BV barely covered by CT before going to umbilical cord which can form knot
placental abruption
premature separation of normally implanted placenta
- hemorrhage into decidua basalis leads to premature placental separation and bleeding
- can impair oxygenation of fetus
placenta previa
implantation of placenta over cervical os
placenta accreta
trophoblastic invasion into mymetrium
placenta increta
trophoblastic invasion through myometrium
placenta percerta
trophoblastic invasion through the uterine wall and into extrauterine space
uterine atony
uterine contractions that usually constrict spiral arteries are not strong enough so postpartum bleeding occurs
predisposing factor of uterine atony and treatment
uterine fibroids and enlargement of uterus
-infusion of oxytocin
placental calcification and risk factor
placenta seems to be programmed to calcify
- if pregnancy last past 40 weeks can happen
- smoking is risk factor
lithopedion
ectopic pregnancy with fetus to large to reabsorb so body calcifies it
gestational trophoblastic disease
benign and malignant neoplasms arising from fetal tissue invading maternal host
- trophoblastic tissue
- elevated B-hCG is marker
complete mole (2)
egg w/ no chrom fertilized by 2 sperm or by 1 sperm that duplicates chroms
partial mole
fertlization of haploid ovum and duplication of paternal hap chroms
-extra male chroms
complete mole fetal tissue
absent
complete mole hydropic villi
extensive grapelike clusters
complete mole trophoblastic hyperplasia
extensive with significant atypia
partial mole fetal tissue
present
partial mole hydropic villi
limited and focal
partial mole trophoblastic hyperplasia
focal with mild atypia
malignant GTDs: invasive mole
invasion into myometrium of villi, covered with layers of prolif trophoblastic cells, b-hCG moderately elevated
choriorcarcinoma
admixture of malignant cytotrophoblast and SCT, no villi
