Fertilization Flashcards
What is the optimal time to inseminate?
6 or more hours before ovulation.
Why is 6 hours pre-ovulation the optimal time?
6 hours is the minimum required time for the capacitation of fresh sperm.
How is frozen sperm different from fresh sperm in terms of capacitation?
Frozen sperm is partially capacitated when thawed.
What is capacitation?
The changes within sperm that confer upon it the ability to acrosome react in response to the appropriate stimulus(binding to the zona pellucida).
Where does capacitation begin and end for anterior vagina deposition?
Begins in the cervix and ends in the isthmus.
Where does capacitation begin and end for cervical/uterine deposition?
Begins in the uterus and ends in the isthmus.
Is capacitation reversible?
Yes.
Does capacitation change sperm morphology?
No.
What motility change occurs during capacitation?
Hyperactivation due to increased cAMP and power output.
What is the purpose of hyperactivation?
To increase the chance of the sperm meeting the oocyte due to the sperm moving in a non-linear fashion.
What are the steps of fertilization?
- Hyperactive motility.
- BINDING of the sperm to the zona pellucida.
- Acrosome reaction.
- Sperm penetration through the zona pellucida.
- Sperm-oolema (oocyte membrane) FUSION.
- Oocyte engulfs sperm.
- Decondensation of the sperm nucleus.
- Formation of the male pronucleus.
What is the biochemical classification of zona proteins?
Glycoproteins.
How many zona proteins do most animals have?
Most have 3, but some have 4.
What is the function of ZP1 and ZP2?
To maintain the structural integrity of the zona pelluicida.
What is the function of ZP3?
An extramembrane receptor for sperm.
What are the steps of sperm binding to the zona pellucida?
- Initially, the sperm and oocyte are loosely associated.
- Sperm binds to ZP3 on the zona pellucida.
- An acrosome reaction is initiated.
- Sperm penetrates the zona pellucida at an oblique angle.
What does acrosin do?
It dissolves portions of the zona pelluicda.
What does hyaluronidase do?
It breaks the connections between cumulus cells.
Why is the angle of the hole(s) in the zona pellucida important?
It allows the zona pellucida to be closed during embryonic growth.
What is the perivitelline space?
The space between the zona pellucida and the oocyte.
What are the steps of sperm-oocyte fusion?
- Right before membrane fusion, sperm settle on microvilli on the oolema. Cortical granules migrate from the cytoplasm to the membrane.
- Oolema fuses to the equatorial segment. Oolema engulfs the sperm cell.
- Nuclear membrane of the sperm cell goes away. Decondensation of the sperm nucleus.
What is the signal for meiosis two resumption?
The release of cortical granules due to a Ca2+ second messenger system.
Where does the phospholipase C zeta come from?
The sperm.
What is a fast block?
The change in the electrical charge across the membrane.
What is a slow block?
The release of cortical granules that lead to sperm being unable to bind to the zona pellucida.
What is syngamy?
The fusion of the male pronucleus and the female pronucleus.
What is a zygote?
When the oocyte has been fertilized, but cell cleavage has not occurred.
What is the lifespan of an oocyte after ovulation?
6-12 hours.
What is the lifespan of sperm after ejaculation?
24-48 hours.
What is the latest possible time that a mare can inseminated?
16 hours after ovulation.
