Question

After a sperm has penetrated an ovum in the process of fertilisation, entry of further sperms is prevented by

• A. Development of the pigment coat
• B. Development of the vitelline membrane
• C. Condensation of yolk
• D. Formation of fertilisation membrane

Answer 1

Answer: (D)

Formation of fertilisation membrane

When one sperm enters the plasma membrane of the egg, the cortical granules fuse in the perivitelline space and release their contents in this space. This space gets hardened and forms the fertilisation membrane which is impermeable for any other sperm. This prevents polyembryony due to the entry of multiple sperms.

Thus, the correct answer is option D.