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FOM
Embryology
18
Medical
Graduate
06/13/2011

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Term
Fertilization
Definition
process by which the male and female gametes (spermatozoa and oocyte) fuse
oocyte (plus corona radiate cells ) is ovulated from the ovary and swept into the uterine tube
spermatozoa must undergo Capacitaion and acrosome reaction
fertilization occurs 12-24 hours following ovulation and occurs in the ampulla of the uterine tube
Term
Capacitation
Definition
conditioning in female reproductive tract that allow sperm to pass through the corona cells and undergo acrosome rxn
removal of glycoprotein coat and seminal plasma proteins from sperm overlying acrosome region
Term
Acrosome Rxn
Definition
leads to release of enzymes (acrosin- and typsin-like substances) needed to penetrate the zona pellucida
sperm bind to zona pellucida; mediated by ZP3 (enzyme release)--> sperm contacts plasmam membrane)
Term
Following Fertilization: Cortical and Zona Rxns
Definition
when the sperm head contacts oocyte surface:
contact leads to release of lysosomal enzymes form crotical granules lining oocyte plasma membrane (Cortical rxn)
oocyte membrane becomes impenetrable to other sperm
zoan pellucida properties are altered to prevent further binding and penetration by other sperm (Zona Rxn)
Term
Sex determination
Definition
XX (female) XY (male)
Term
8 cell zygote stage (murula)
Definition
cell-cell contacts are maximized, segregation of inner and outer (differentiating) cells(become trophoblast)
Inner cells communicate via gap junctions (form the embryo)
Term
Trophoblast
Definition
what will become the placenta
Term
Blastocyst Dev.
Definition
distinct outer (trophoblast) and inner (embryo) cell mass (localized to one pole)
fluid penetration into intercellular spaces of Icm results in blastocele = blastocyst
Term
Penetration into uterine mucosa
Definition
done by trophoblast cells at embryonic pole of the blastocyst (6 days)
Term
Implantation of blastocyst
Definition
mediated by L-selectins and their receptors, and EMC molecules and thir integrin receptors
Term
Corpus luteum
Definition
provuces progesterone, which stimulaates secretory activity of endometriumand is highly vascular
Term
Week two human blstocyst at day 7.5
Definition
partially embedded in the endometrial stroma.
trophoblast inner layer (cytotrophoblast) and an outer syncytiotrophoblast. THe embryoblast is formed by the epiblast and hypoblast and there is also an amniotic cavity developed
Term
Cytotrophoblast and Syncytiotrophoblast
Definition
cytotrophoblast - mononucleated cell layer; dive and migrate to syncytiotrophoblast
Syncytiotrophoblast; outer, multinucleated cell layer; produce human chorionic gonadotropin (maintains the corpus colusum causing it to release progesterone)
Term
Human blastocyst at day 9
Definition
deeper embedment; lacunae start to develop in the syncytiotrophoblast
the original entrance defect is closed by a fibrin coagulum
Term
Blastocyst at day 12
Definition
syncytiotrophoblast erode maternal capillaries
trophoblast lacunae connect to maternal sinusoids
blastocyst start to protrude into uterus lumen
extraembryonic cavity develops outside the exocoelomic cavity
Term
Blastocyst at day 13
Definition
secondary yolk sac forms within exocoelomic cavity
exocoelomic cyst - portions of "pinched off" exocoelomic cavity
Lacunae are present at both poles
Uteroplacental circulation has begun
Term
Blastocyst at day 1
Definition
Term
Abnormal implantation sites
Ectopic pregnancies
Definition
occur outside of the uterus; the embryo usually dies in second month of gestation
abdomincal cavity, ampullary region, interstitial implantation, ovarian implantation
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