Fertilization

Question 0

How can you tell, looking at an ovum in a microscope, that it has reached meiosis I?

Answer 0

Loss of the germinal vesicle(s?)

Question 1

3 proteins in the zona pellucida?

Answer 1

ZP1, ZP2, ZP3… they seem to still be finding them.

Question 2

Consideration when actually doing the process of ICSI?

Answer 2

Don’t damage the spindle, which will be near the polar body.

Question 3

Can sperm taken straight from the epididymus fertilize an egg?

Answer 3

No, they need to capactitated.

Question 4

How much time do the sperm spend in the epididymus?

Answer 4

About 3 mo.

Question 5

Where does capacitation occur?

Answer 5

Within the female reproductive tract.

Question 6

How long is take sperm to get to the oviducts after ejaculation?

Answer 6

About 5 minutes. probably.

Question 7

Changes in capacitation of sperm?

Answer 7

less cholesterol in membrane
changes in some proteins
increased pH
but… most visibly: Increased motility (due to increased cAMP)

Question 8

What enzyme helps capacitated sperm penetrate the cumulus oophorous?

Answer 8

PH20 - a hyaluronidase.

note that it might be a team effort from the sperm

Question 9

What does the acrosome reaction do?

Answer 9

Releases enzymes that digest the ZP.

Question 10

Aside from ZP penetration, what else does the acrosome reaction allow?

Answer 10

Exposures sperm head, allowing it to bind with receptors on the egg plasma membrane.

Question 11

2 things a sperm must have to penetrate the ZP?

Answer 11

Motile force.

Digestive enzymes.

Question 12

What’s ACE got to do with fertilization?

Answer 12

ACE releases GPI-anchored sperm proteins PH20 and TESP-5 (a serine protease).
(probably not that important)

Question 13

In what orientation does the sperm head hit the ovum plasma membrane? Why does this matter?

Answer 13

Side-on. That’s where particular necessary adhesion molecules are.

Question 14

What 2nd signaling events happen when the sperm enters the egg?

Answer 14

PLC -> IP3 -> Ca++ influx…

Question 15

Changes that happen during egg activation?

Answer 15

Exocytosis of cortical granules (polyspermy block).
Cytoskeletal rearrangement.
Switching from meiosis -> mitosis.

Question 16

How often does polyspermy occur?

Answer 16

1-2% of time.

Question 17

In the lecture, what was a thing that predisposed the egg to polyspermy?

Answer 17

Cortical granules not being evenly throughout the egg membrane.

Question 18

At what levels does block to polyspermy occur in humans?

Answer 18

Block to polyspermy occurs both at ZP and egg plasma membrane.

Question 19

Can eggs be activated without fertilization?

Answer 19

Yeah. Physical manipulation etc. etc. can set off activation.

Question 20

4 steps in intrauterine insemination?

Answer 20

Get the sperms.
Put them in some capacitating buffers.
“Swim-up” techniques to select the winners.
Put ‘em in.

Question 21

What’s ICSI?

Answer 21

Intracytoplasmic Sperm Injection

-single spermatozoan into egg.

Question 22

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?

Answer 22

Pentoxyphylline activates.
TESE - from testis
PESE - from epididymus.
Must use ICSI.