Quiz 5 Lecture Notes Flashcards
gamete transportation: barrier 1
- cervical mucus
- only strong sperm can swim through
gamete transportation: reservoir 1
- cervical crypts
- sperm colonized in the crypts and only motile/healthy sperm can keep moving
gamete transportation: barrier 2
endometrial glands
gamete transportation: reservoir 2
- isthmus
- very narrow, sperm will attach here, they then must become hyperactive to be released and go to the site of fertilization
gamete transportation: barrier 3
uterotubal junction
gamete transportation: barriers
1 - cervical mucus
2 - endometrial glands
3 - uterotubal junction
gamete transportation: reservoirs
1 - cerival crypts
2 - isthmus
where is sperm ejaculated?
vagina
steps of gamete transportation: immediate transport
- site of ejaculation (vagina)
- sperm are loss or move towards the cervix
steps of gamete transportation: cervix
removal of non-motile and abnormal sperm
steps of gamete transportation: uterus
capacitation initiated
steps of gamete transportation: oviduct
- capacitation completed
- hyperactive motility
steps of gamete transportation: fertilization
- acrosome reaction
- sperm penetrates oocyte
- male and female pronuclei form
steps of gamete transportation
(how the sperm moves through the female reproductive tract)
- immediate transportation
- cervix
- uterus
- oviduct
- fertilization
where to deposit sperm during artificial insemination?
the body of the uterus
(uterine horn has the same success but better to do uterus)
oocyte transport through the oviduct
- egg is picked up by the infundibulum
- moved into the ampulla (wide part)
- isthmus is very narrow and has strong muscle to contract so that it can trap the egg at the ampullary isthmus junction (site of fertilization)
important events of fertilization
- capacitation
- sperm penetration between cumulus cells
- sperm attatchment to the zona pellucida
- sperm penetration to zona pellucida
- fusion of sperm and oocyte
why is capacitation important?
- surface molecules exposed can attach to the egg
- hyperactivity
capacitation
glycoprotein layer is removed
how is the glycoprotein created around the sperm?
sperm coming from the epididymis has surface molecules, the glycoprotein coating is created by seminal plasma in the colliculus seminalis
cumulus cells are rich in hyaluronic acid. What enzyme is needed to help sperm penetrate the cumulus cells?
hyaluronidase enzyme
ZP 1
structural support
ZP 2
helps an acrosome reacted sperm move through the zona
ZP 3
zona protein that binds to a receptor on the sperm plasma membrane and induces the acrosome reaction
why is ZP 3 important?
important for attatchment of sperm and induce acrosomal reaction
acrosome reaction
release of enzymes needed to penetrate the zona pellucida
sperm has receptors to bind to ______ and attaches to the zona pellucida
ZP3
acrosomal reaction: before reaction
acrosomal cap covers the head of sperm (inner and outer acrosomal membrane present)
acrosomal reaction: during reaction
the plasma and outer acrosomal membrane fuse together, vesicles are formed, enzymes are released
acrosomal reaction: after reaction
- enzymes degrade the zona pellucida and sperm move inside
- the sperm no longer have a plasma membrane, the inner acrosomal is what is left of the equatorial segment
fusion of gamete membranes
(what order of events will occur at/after fusion)
- sperm penetration of vitelline membrane
- formation of pronuclei
- syngamy
syngamy
pronuclei of sperm and egg come together
for the fusion between sperm and egg, need a protein on the sperm called ________ and a receptor on the egg called ______
Izumo, juno
male/sperm protein to bind to the vitelline membrane
izumo
female/egg receptor to bind to the vitelline membrane
juno
if _______ is inhibited, the sperm can go through the zona pellucida because ZP3, however it could not fuse with the vitelline membrane
izumo
gamete transportation of fertilization
(sperm)
- hyperactive motility
- binding to zona pellucida
- acrosomal reaction
- penetration of zona pellucida
- sperm-oocyte membrane fusion
- release of second polar body
- sperm engulfed
- formation of male and female pronucleus
why must there be blockage of polyspermy?
only one sperm can fertilize an egg otherwise the embryo will die
methods of block go polyspermy
- zona reaction (cow, pig)
- vitelline block (rabbit)
- zona reaction and vitelline block (rats and mice)
mechanism of block of polyspermy
cortical reaction
cortical reaction
after binding to the membrane, sperm stimulates the calcium ion in the oocyte which stimulates the release of cortical granules that contain enzymes that degrade receptors so sperm cannot bind to the zona pellucida)
early embryonic development
(the stages of the cells as the grow)
one cell, two cell, four cell, eight cell, sixteen cell, morula, tight morula, early blastocyst, blastocyst, expanded blastocyst, hatching blastocyst
location: one cell, two cell, four cell
ampullary-isthmic junction
location: eight cell and sixteen cell
isthmus
when does the embryo enter the uterus?
around day 5, the morula will enter the uterus
zygote vs egg
egg has one polar body, a zygote has two polar bodies because it has been fertilized
morula
cells become different from each other
chimera
the offspring of when 2 morulas are fused together
what would occur is you separated blastomeres?
identical twins
compaction of the morula
pre-compact you can see the boundaries of the cells, after compaction you cannot see boundaries as cells are tightly compacted creating sealing
why does compaction occur, what is the purpose of sealing?
needed so that fluid can accumulate and not leak
important structures in the blastocyst
- blastocoel
- inner cell mass
- trophoblast
blastocoel
fluid filled cavity in the blastocyst
inner cell mass
forms the embryo
trophoblast
forms placenta