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Exocytosis of cortical granules
 CG are membrane‐bound organelles, derived from the Golgi apparatus
 Transported to oocyte cortex via 2 pathways
o Cytoplasmic actin network
o cortical granules ‘hitchhike’ on Rab11a vesicles that move to the plasma membrane
 Disruption of cortical granule translocation severely impairs the ZP block to polyspermy
Control Mutant
(Cheeseman et al. 2016)
Exocytosis of cortical granules
 Hardening of the ZP
 Slow‐acting block to polyspermy (>1hr)
 Exocytosis of enzymes (proteinase, overperoxidase, p75) (Hoodbhoy and Talbot 1994)
 Cleavage of ZP2 protein leads to lower binding affinity of sperm (Avella et al. 2014)
 CG exocytosis occurs following Ca2+ rise during oocyte activation
 Does not require sperm‐egg plasma membrane binding
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PRECONGRESS COURSE 02 I VIENNA, AUSTRIA – 23 JUNE 2019 35