Jan 22: Fertilization in mammals
Several proteins on sperm head may mediate its attachment to zone pellucid such as
- Galactosyltransferase enzyme on sperm plasma membrane - Zonadhesin protein - Fertilin (ADAM2 + ADAM3 proteins)!
Explain how FAST BLOCK happens to polyspermy
- occurs in sea urchin & amphibian eggs; NOT in mammals - fast block is activated within a few seconds (1-3 sec) after sperm contact
explain how SLOW BLOCK happens to polyspermy
- occurs in sea urchins, amphibians and mammals -
How is polyspermy prevented during fertilization? (changes in egg that prevent fertilization by more than 1 sperm.)
FAST BLOCK SLOW BLOCK
Sperm Capacitation
Fluids of uterus/oviduct that induces change in the sperm thus allowing it to fertilize the egg
What happens during Sperm-Egg Adhesion?
Sperm attach to ZP2 and ZP3 glycoproteins on zona pellucida of the egg
Where does fertilization in mammals occur?
fertilization occurs internally in ampulla of oviduct
Rearrangement of Egg Cytoplasm occurs when
occurs after sperm has entered the egg
Rearrangement of Egg Cytoplasm may lead to
regionalized redistribution of "cytoplasmic determinants" (e.g. mRNAs or proteins in egg cytoplasm that influence the future fates of cleaving blastomeres)
