The sperm binds through the corona radiata, a layer of follicle cells on the outside of the secondary oocyte. The corona radiata sends out chemicals that attract the sperm in the fallopian tube to the oocyte. It lies above the zona pellucida, a membrane of glycoproteins that surrounds the oocyte.

Cone of attraction and perivitelline membrane

Where the spermatozoon is about to pierce, the yolk (ooplasm) is

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