A) Cells of corona radiata trap all sperms except one
B) Only two sperms nearest the ovum penetrate zona pellucida
C) Secretions of acrosome helps one sperm enter cytoplasm of ovum through zona pellucida
D) All sperms except the one nearest to ovum loose their tails
Correct Answer: C
Solution :
The acrosomal reaction normally takes place in the ampulla of the Fallopian tube (site of fertilization when the sperm penetrates the secondary oocyte. A few events precede the actual acrosome reaction. The sperm cell acquires a 'hyperactive motility pattern' by which its flagellum produces vigorous whip-like movements that propel the sperm through the cervical canal and uterine cavity, until preaches the isthmus of the Fallopian tube. The sperm approaches the ovum in the ampulla of the fallopian tube with the help of various mechanisms, including chemotaxis. Glycoproteins. on the outer surface of the sperm then bind with glycoproteins on the zona pellucida of the ovum. The first stage is the penetration of corona radiata, by releasing hyaluronidase from the acrosome to digest cumulus cells surrounding to oocyte and exposing acrosin attached to the inner membrane of the sperm. The cumulus cells are embedded in a gel-like substance made primarily of hyaluronic acid, and developed in the ovary with the egg and support it as it grows. After reaching the zona pellucida the actual acrosome reaction beings.
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