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Flashcards in Fertilization Deck (13)
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1

Protamines

found in sperm head

Specialized basic histone tightly held together by disulfide bond cross-linking

2

Axial filament of sperm tail

9+2 array of microtubules typical of cilia and flagella

*kartageners ciliary defect
- tx for infertility: inject non-motile sperm into egg

3

In order to deposit sperm we need what 3 things?

1. Sufficient number
2. Motility
3. Morphology

4

[ ] of semen should be? How many of that needs to be motile?

How many need to look normal (morphology)?

Ejaculate volume: 2 ml

Sperm [ ]:
>20x106/ml (20 mill)

Sperm motility: > 50% need to be motile

Morphology:
14% nl

5

Sperm capacitation

process where spermatozoa acquires the capacity to undergo the acrosome rxn and fertilize eggs
(bind to ZP and undergo acrosomal rxn)
- process occurs in female genital tract

6

Sperm egg intxn

1. SPerm activated by female reproductive tract
2. SPerm binds zona pellucida
3. Acrosomal rxn
4. Sperm lyses hole in zona and penetrates
5. Sperm and egg membrane fuse (oolemma fusion)
6. Intravitelline processing

7

Zona pellucida

Shell like structure that surrounds oocyte
- glycoprotein sheet with several microns thick
1. ZP1
2. ZP2
3. ZP3
- sperm binding to zona is mediated by ZP3

8

- sperm binding to zona is mediated by ___

ZP3

9

Acrosomal rxn:
When outer membrane of the acrosome fuses with the plasma membrane of the sperm, it exposes what? What is the protein responsible for sperm-oocyte fusion?

the contents of the acrosome (hyaluronidase and acrosin)
- Involves G prot VGCC

Fertilin: responsible for sperm-oocyte fusion

10

2nd meiotic division happens when?

oolemma is penetrated

11

Sperm head has a very highly condensed chromatin in the nucleus, what molecule is responsible for keeping it condensed?

Protamine
- a specialized histone that tightly wraps DNA by disulfide bonds

*these bonds are reduced by the action of oocyte-derived glutathione and the sperm nucleus decondenses

12

What rxn prevents more sperm fertilization? (polyspermy)

The zona rxn:
- egg releases cortical granules (lysosomal enzymes) and forms new glycoprotein ZP3-F
(which is NOT capable of binding sperm like ZP3)

13

Chromatin w/in the mature sperm nucleus was kept tightly packed with disulfide bonds (via protamines), what reduces these bones?

Oocyte activation and completion of meiosis

bonds are reduced by the action of oocyte-derived glutathione and the sperm nucleus decondenses