Fertilization

Question 1

-Penetration of cumulus granulosa cells and corona radiata
-the fusion of plasma membrane and outer acrosomal membrane
-exposure of inner acrosomal membrane
-penetration of zona pellucida
-acrosome swells and is lost

Answer 1

acrosome reaction

Question 2

Corona penetrating enzyme

Answer 2

hyaluronidase

Question 3

ZP3 function

Answer 3

sperm receptor

Question 4

ZP2 function

Answer 4

initiates acrosome reaction

Question 5

Where specifically does fertilization occur in the female reproductive tract?

Answer 5

ampulla-isthmus junction

Question 6

What are the 4 key events for successful fertilization?

Answer 6

1. acrosome reaction
2. Zona reaction
3. vitelline block
4. pronuclear development & syngamy

Question 7

One of the main enzymes in acrosome reaction that acts to dissolve the zona pellucida

Answer 7

Acrosin

Question 8

What are the 2 blocks of polyspermy?

Answer 8

zona reaction & vitelline block (in order)

Question 9

How are the zona reaction and vitelline block initiated?

Answer 9

by penetration of the sperm

Question 10

What happens during the zona reaction?

Answer 10

-cortical granules are released into the perivitelline space and produce calcium ions
-Ca increase downregulates ZP3 so no more binding can occur (“hardens” the ZP)

Question 11

Effectiveness of the zona reaction decreases with… (what 2 factors?)

Answer 11

age & temperature (alters rate of calcium release)

Question 12

What is the vitelline block?

Answer 12

After the vitelline membrane engulfs one sperm cell, a signal is sent that prevents the vitelline membrane from engulfing any more sperm cells

Question 13

What is syngamy/dance of syngamy?

Answer 13

when pronuclei of male and female migrate toward the center to form a single nucleus (zygote-diploid)

Question 14

What are the 6 steps of fertilization?

Answer 14

1. sperm squeezes through cells left over from follicle
2. acrosomal enzymes digest the egg’s jelly coat
3. proteins on the sperm head bind to the eggs receptors
4. plasma membranes of the sperm and egg fuse
5. sperm nucleus enters the egg cytoplasm
6. fertilization envelope forms

Question 15

Too many sperm entering one egg

Answer 15

polyspermy

Question 16

The Vitelline Block occurs when the sperm binds to the Zona Pellucida.

Answer 16

False; occurs when sperm penetrates the oocyte

Question 17

Change in ______ alters the direction of contractions in the oviduct

Answer 17

E2:P4 ratio
-High E2, low P4: towards infundibulum
-Low E2, high P4: towards uterine horn (for implantation)

Question 18

What proteins of the zona pellucida are targeted by contraceptives and why?

Answer 18

ZP3: prevents sperm from docking & therefore penetrating ZP
ZP2: prevents the acrosome reaction so sperm can’t penetrate the oocyte