Fertilization and Gastrulation Flashcards
corona radiata
surround ovum, follicles from mom
zona pellucida
glycoprotein layer of ovum
perivitelline space
between PM and zona pellucida of ovum
acrosome
part of head of sperm, contains enzymes
middle piece of sperm
part of tail, have mitochondria
fertilization occurs in the
ampula (distal 1/3 of fallopian/uterin tube)
capacitation
glycoprotein coat and seminal plasma proteins removed from PM of head of sperm, need this to happen to release acrosome enzymes (acrosome reaction)
sperm release ____ to penetrate corona radiata
hyaluronidase (and mucosal proteins)
sperm release _____ to penetrate zona pellucida
esterases, acrosin, neuraminidase
zona reaction
block to polyspermy, granules are released by egg into perivitelline space, react with zona, zona changes configuration into solid meshwork to block other sperm
cleavage happens ___ hours after fertilization
30
fertilization takes approximately ___ hours
24
cleavage
inc in cell #, dec in cell size embryo size unchanged morula development (day 3)
day 4
morula enters uterus
zona pellucida starts to degenerate around day __
5
late blastocyst
day 7, NO zona pellucida (embryo “hatches”)
cells of trophoblast give rise to ______
the placenta
early pregnancy factor
immunosuppressive, can use to detect
cytotrophoblast
eventually replaces trophoblast
stem cell layer, mitotically active
give rise to syncytiotrophoblast
syncytiotrophoblast
release proteolytic enzymes that start to erode into uterine lining
responsible for implantation and initial signal of pregnancy (release hCG)
complete hydatidiform mole results from
1) fertilization of an EMPTY oocyte followed by duplication of the sperm or 2) fertilization of an EMPTY oocyte by 2 sperm
what is a hydatidiform mole and what can it lead to
abnormal proliferation of trophoblast, excessive amounts of hCG produced
can lead to choriocarcinomas
partial hydatidiform mole results from
fertilization of a NORMAL oocyte by 2 sperm
inner cell mass
gives rise to epiblast (ectoderm, amnion, amniotic cavity)
intraembryonic
hypoblast
extraembryonic endoderm, only exists during week 2
prechordal plate, primary and secondary yolk sac, extraembryonic mesoderm
extraembryonic somatic mesoderm
lining trophoblast and covering amnion
extraembryonic splanchnic mesoderm
lining yolk sac
connecting stalk
formed from EE somatic mesoderm, becomes umbilical cord
primitive blood
formed from EE splanchnic mesoderm, forms in wall of yolk sac
chorion
formed from EE somatic mesoderm, cytotrophoblast, syncytiotrophoblast
layer of the placenta
placenta previa
implant too close to the cervic
internal os: near uterus
external os: near cervix
suggest C section
give rise to all 3 germ layers
epiblast
why do the prechordal plate and cloacal membrane die?
no component of mesoderm=no blood supply
septum transversum
mesoderm, becomes part of diaphragm
cardiogenic area
mesoderm, becomes heart, forms cephalad to prechordal plate
chordomas
neoplasms of bone that arise from remnants of notochord, occur in axial skeleton in spheno-occipital region of skull and sacral regions
paraxial mesoderm gives rise to…
somites (myotomes, sclerotomes, dermatomes)
intermediate mesoderm gives rise to…
urogenital (kidney, gonads)
lateral plate mesoderm gives rise to…
connective tissue (blood, lymph, mesenteries, CV)
