Fertilization Flashcards
How can you tell, looking at an ovum in a microscope, that it has reached meiosis I?
Loss of the germinal vesicle(s?)
3 proteins in the zona pellucida?
ZP1, ZP2, ZP3… they seem to still be finding them.
Consideration when actually doing the process of ICSI?
Don’t damage the spindle, which will be near the polar body.
Can sperm taken straight from the epididymus fertilize an egg?
No, they need to capactitated.
How much time do the sperm spend in the epididymus?
About 3 mo.
Where does capacitation occur?
Within the female reproductive tract.
How long is take sperm to get to the oviducts after ejaculation?
About 5 minutes. probably.
Changes in capacitation of sperm?
less cholesterol in membrane
changes in some proteins
increased pH
but… most visibly: Increased motility (due to increased cAMP)
What enzyme helps capacitated sperm penetrate the cumulus oophorous?
PH20 - a hyaluronidase.
note that it might be a team effort from the sperm
What does the acrosome reaction do?
Releases enzymes that digest the ZP.
Aside from ZP penetration, what else does the acrosome reaction allow?
Exposures sperm head, allowing it to bind with receptors on the egg plasma membrane.
2 things a sperm must have to penetrate the ZP?
Motile force.
Digestive enzymes.
What’s ACE got to do with fertilization?
ACE releases GPI-anchored sperm proteins PH20 and TESP-5 (a serine protease).
(probably not that important)
In what orientation does the sperm head hit the ovum plasma membrane? Why does this matter?
Side-on. That’s where particular necessary adhesion molecules are.
What 2nd signaling events happen when the sperm enters the egg?
PLC -> IP3 -> Ca++ influx…
Changes that happen during egg activation?
Exocytosis of cortical granules (polyspermy block).
Cytoskeletal rearrangement.
Switching from meiosis -> mitosis.
How often does polyspermy occur?
1-2% of time.
In the lecture, what was a thing that predisposed the egg to polyspermy?
Cortical granules not being evenly throughout the egg membrane.
At what levels does block to polyspermy occur in humans?
Block to polyspermy occurs both at ZP and egg plasma membrane.
Can eggs be activated without fertilization?
Yeah. Physical manipulation etc. etc. can set off activation.
4 steps in intrauterine insemination?
Get the sperms.
Put them in some capacitating buffers.
“Swim-up” techniques to select the winners.
Put ‘em in.
What’s ICSI?
Intracytoplasmic Sperm Injection
-single spermatozoan into egg.
What is used to activate sperm in TESE/PESE? (What’s the difference between TESE and PESE?) Can these sperm be put into droplet or must you use ICSI?
Pentoxyphylline activates.
TESE - from testis
PESE - from epididymus.
Must use ICSI.
