Why does fertilization of an oocyte typically result in blocking polyspermy, preventing multiple sperm from entering?

💡 Explanation

Fertilization causes a cortical reaction, where cortical granules release enzymes. This alters the zona pellucida, preventing other sperm from binding because the receptors are changed. Therefore, polyspermy is blocked, rather than simply destroying sperm or weakening the zona without changing its structure.

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