Fertilization and Pregnancy Recognition II

Question 1

What is capacitation defined as?

Answer 1

Membranous and molecular changes that prepare sperm to fertilize an egg

Question 2

What occurs in male repro tract to with regards to capacitation?

Answer 2

Sperm acquire new coating of proteins

Question 3

What occurs to sperm movement upon capacitation?

Answer 3

Hypermotility = Turn in circle

Question 4

What occurs to non-capacitated sperm in the oviduct?

Answer 4

Proteins on the sperm bind to the oviduct wall and keep the sperm until it is capacitated

Question 5

2 steps of oocyte transport?

Answer 5

Pick up

Transport to the oviductal ampulla

Question 6

Explain oocyte pick up

Answer 6

Oocytes are picked up from the surface of the ovary by the fimbria

Question 7

How is oocyte transported through oviduct to uterus?

Answer 7

Ciliated cells beat and move the oocyte down - no need of contractions

Question 8

7 categories of sperm and egg interaction

Answer 8

1. Capacitation(chemotaxis)
2. Cumulus penetration
3. Zona binding
4. Acrosome reaction
5. Zona penetration
6. Gamete binding and fusion
7. Cortical granule release and zona reaction

Question 9

How is sperm chemotaxis effected by capacitation?

Answer 9

Non-capacitated sperm have lower probability to find the oocyte

Question 10

Role of cumulus layer surround oocyte?

Answer 10

Protect against uncapacitated sperm and promote sperm motility

Question 11

What is a major component of cumulus and how does sperm overcome this?

Answer 11

Hyaluronan

Sperm have hyaluronidase enzymes

Question 12

What is the zona pellucida considered as?

Answer 12

Species specific barrier - if you dont have the right receptors, cant enter

Question 13

What 3 glycoproteins is zona pellucida made up of?

Answer 13

ZP-1,ZP-2, ZP-3

ZP3 is protein that sperm bind to

Question 14

Can uncapacitated sperm bind to zona pellucida?

Answer 14

Yes, but interaction is weak

Question 15

Explain the acrosome reaction

Answer 15

Acrosome contents are released as fusion between sperm and occyte increases. The hydrolytic enzymes released from the acrosome digest the zona pellucida and allow sperm to enter the egg

Question 16

3 possible methods of zona penetration?

Answer 16

1. Mechanical - brute force
2. Sperm factor and flagellar motility - zp structures get reorganized
3. Acrosomal enzymes - most likely method

Question 17

What occurs as sperm binds to oocyte membrane?

Answer 17

Membrane depolarizes
Ca signal within oocyte
Cortical granules released which block entrance of other sperm

Question 18

What occurs to sperm during fusion with oocyte membrane?

Answer 18

Entire sperm enters

Entire sperm structure is digested except DNA and RNA if present (mitochondria digested)

Question 19

How do cortical granules prevent entrance of more sperm?

Answer 19

Contain enzymes which modify structure of ZP

Question 20

How can you tell you have successful fertilization?

Answer 20

2 polar bodies visible

Question 21

Effect of oviductal microenvironment on fertilized egg?

Answer 21

Increased cleavage rate

Improved hatching of blastocyst

Question 22

How many stages of implantation are there, and what are they?

Answer 22

1. Pre-attachment
2. Apposition
3. Adhesion

Question 23

Affect of IFN-tau?

Answer 23

Represses oxytocin receptors
PGF2alpha production is reduced
Contractions are reduced to minimum

Question 24

How does maternal recognition of placenta occur in pig?

Answer 24

Pig uses estrogen to cause for PGF2alpha to be released into uterus as opposed to blood