Lecture 9- fertilization cont.
- Human zona pellucida is made of 4 major glycoproteins
- ZP4 is a connecting protein. ZP1 and ZP4 are important for structural integrity of the
- Non-growing oocyte = possibly a primary oocyte that has completed mitosis (and is
paused in prophase I?)
- ZP protein genes are only expressed during the time period the zona pellucida is
- Up to 50 enzymes in the sperm acrosome have been discovered, there may be many
more yet to be identified.
- By the time fertilization happens, cumulus oophorus drops off.
- Prior to sperm contacting the egg, it contacts the corona radiata. But what triggers the
acrosome reaction is the contact with the zona pellucida.
- When the sperm touches the membrane of the egg, most of the acrosome has already
vesiculated so what touches are the sperm membrane and the egg’s cell membrane.
- Sperm has to be able to contact the ZP and to stay attached to it.