Blocks to Polysermy Flashcards
1
Q
What 2 mechanisms ensure monospermy
A
Fast block - electric fence
Slow block - castle moat
2
Q
What happens in the fast block
A
As soon as one sperm penetrates, sodium ions rush into the ovum causing membrane to become depolarised.
3
Q
Describe the slow block
A
Calcium ions are released by ovums ER into its cytoplasm.
Cortical granules located under ovum membrane spill enzymes called zonal inhibitory proteins into extracellular spaces
Enzymes attract water and deters sperm
Enzymes also destroy sperm receptors
CORTICAL REACTION
4
Q
Polyspermy is what
A
Entry of several sperm into a single egg
