Reproduction Final Part 3 (Pozor) Flashcards
Name a major function of the utero-tubal junction.
Delays capacitation until ovulation
T/F: In the presence of progesterone, sperm storage is not necessary and may be eliminated.
TRUE
Define: Capacitation
Changes that must occur in sperm before they are able to attach and penetrate an ovum.
Name some changes that occur during capacitation.
- Loss of membrane cholesterol
- Increase in pH
- Changes in intracellular Ca++
- Activation of protein kinase A
- Polymerization of globular actin to filamentous actin
Name some important molecules found in oviductal fluid.
- Albumin
- NaHCO3
- Ca++
An O-linked oligosaccharide attached to a ZP3 protein appears to be directly related to what?
Sperm-binding specificity
What glycoprotein is the sperm receptor?
ZP3
What occurs in secondary binding of sperm?
Sperm bind to ZP2 receptors on the inner acrosomal membrane. This allows sperm to travel through the zona pellucida.
Name a believed function of hyaluronidase.
Dissolve the hyaluronic acid complex matrix of cumulus cells surrounding the oocyte.
What two major steps must a sperm complete to be able of fusing with the plasma membrane of an oocyte?
- Acrosome reaction
- Penetration of the zona pellucida
Describe the significance of the sperm equatorial segment.
This part of the sperm fuses with the egg plasma membrane.
Describe the “slow block”.
Once a sperm has successfully fused with an oocyte, there is an immmediate increase in intracellular Ca++, which causes cortical granule exocytosis. This causes the oocytes coat to toughten and deactivate both ZP3 and ZP2 glycoproteins.
Describe the “fast block”.
When a sperm fuses with the vitteline membrane and there are changes in membrane polarization which inhibits fusion by other sperm.
Describe the formation of the female pronucleus.
After a sperm has fused, the oocyte reacts to the rising intracellular levels of Ca++ by completing meiosis II and surrounding the non-polar body by a nuclear membrane.
Describe the formation of the male pronucleus.
Once paternal chromatin is exposed directly to ooplasm, decondensation occurs and a new nuclear membrane is formed.