how dose zona pellucida of ovum help in preventing polyspermy
Answers
Zona pellucida is the outer membrane of ovum. It can prevent sperm to enter.
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1. During fertilization, when a sperm comes in contact with the zona pellucida layer of the ovum a cortical reaction take place which leads to a modification of the zona pellucida that blocks polyspermy.
2. The acrosomal enzymes released by the head of the sperm begin to dissolve and the actin filament comes into contact with the egg's plasma causes the release of the calcium from the storage site in the egg and raises the intercellular calcium concentration. It triggers the fusion of cortical granules mbrane with the egg's plasma membrane liberating the contents of the granules to the extra cellular space and establishes a permanent barrier to prevent the polyspermy.
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