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Embryology
KU SOM Prematriculation 6/13/11 Lecture
29
Medical
Professional
06/13/2011

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Cards

Term
Where does fertilization likely occur? How long after ovulation?
Definition
In the ampulla of the uterine tube

12-24 hours after ovulation
Term
these are the cells that are ovuulated with the oogyte
Definition
corona radiata
Term
2 steps required for sperm to fertilize the egg
Definition
1) capacitation (conditioning in female reproductive tract) removes glycoprotein coat allowing sperm to pass through corona cells

2) Acrosome Reaction (release of enzymes needed to penetrate the zona pellucida
Term
this protein helps sperm bind to zona pellucida
Definition
ZP3
Term
3 Phases of fertilization
Definition
1) capacitated sperm bind to and penetrate corona radia

2) 1 or more sperm penetrates zona pellcida

3) 1 sperm penetrates oocyte membane leading to fusion of sperm and oocyte cell membranes
Term
what happens when the first sperm gets through the oocyte membrane?
Definition
contact least to release of lysosomal enzymes from cortical granules lining oocyte plasma membrane

oocyte membrane becomes impenetrable to other sperm

zona pellucida properties are altered to prevent further binding and penetration by sperm
Term
How many primary oocyte daughter cells become mature gamate? What do the others become?
Definition
1

polar bodies
Term
After fertilization, how long before the cell devides once, twice?
Definition
1 30 hours, 2 40 hours
Term
why do embryos become compacted?
Definition
cell differentiation
Term
Once cells have formed the morula, what are the inner cells and outer cells called?
Definition
inner: embryo proper or embryoblast

outer: trophoblast
Term
How many days after fertilization do morula cells enter the uterine cavity?
Definition
4
Term
What happens @ day 5?
Definition
fluid penetrates into intercellular spaces creating a blastocele (or blastocyst)
Term
what happens @ day 6?
Definition
trophoblast @ embryonic pole inserts iteself into uterine mucosa
Term
when does the zona pellicula disappear?
Definition
blastocyst stage (4.5-5 days)
Term
what happens to the follicle after it releases the egg?
Definition
turns into the corpus luteum and begins to secrete progesterone
Term
what causes the endometrium to thicken ?
Definition
progesterone secreted by the corpus luteum
Term
what happens at day 7.5?
Definition
trophoblast is now 2 layyers (cytotrophoblast single layer of stem cells and syncytiotrophoblast multinucleated area, in the endometrium)


embryo also splits into 2 layers, epiblast (top) with columnar cells lining the amnionic cavity and hypoblast (bottom) cubiodal cells adjacent to blastocyst cavity
Term
what is the function of unterine glands?
Definition
nourishment
Term
what makes a postive pregnancy test?
Definition
Human chorioning gonadotropin

HCG, emitted by syncytiotrophoblast
Term
what happens @ day 9?
Definition
syncitiotrophoblastic lacunae form

blastocyst cavity is transformed into exocoelomic cavity (primitve yolk sac)
Term
what lines the primitive yolk sac?
Definition
the exocoelomic membrane
Term
what happens @ day 12?
Definition
maternal blood fills synctiotrophoblast lacunae

chorionic cavity develops right outside the exocoelomic cavity, lined by 2 layers of extraembryonic mesoderm
Term
what happens @ day 13
Definition
2ndary yolk sac forms outside primitive yolk sac

primitive yolk sac pinches off becoming exocoelomic cyst

trophoblast forms placental villi, mesoderm protrudes into villi (which eventually becomes blood vessels)

bleeding occurs at implantation site
Term
define ectopic pregnancy, Where do most occur?
Definition
implantation that occurs outside of the uterus. In the fallopian tube
Term
where do abdominal pregnancies typically occur?
Definition
in the rectouturine pouch in the peritonieum between the uterus and rectum
Term
how many cells do morula have
Definition
12-16
Term
how long does zona pellucida last? Why does it leave?
Definition
late moreula stage, so implantation can occur
Term
what does progesterone do?
Definition
causes the glands to thicken in order for implantation to occur
Term
which part of the trophoblast is multinucleated? Which isnt?
Definition
syncytiotrophoblast

cytotrophoblast
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