Question

What happens when many sperms reach closer to the ovum?

• A. All sperms except one lose their tail in order to penetrate the zona pellucida.
• B. Zona pellucida binds with all the sperms and induces acrosome reaction.
• C. Only two sperms are able to penetrate the zona pellucida.
• D. Acrosomal secretion from one sperm helps it to enter inside the ovum by penetrating the zona pellucida.
  

Answer 1

The correct option is D Acrosomal secretion from one sperm helps it to enter inside the ovum by penetrating the zona pellucida.


Millions of sperms are released inside the female reproductive tract that swim and reach the fallopian tube.
If ovum is present in the fallopian tube then one of the sperms enters inside the ovum due to acrosomal reaction.

Acrosome reaction allows the sperm to penetrate the zona pellucida of ovum by release of acrosomal enzymes. After sperm enters inside the ovum, the oocyte releases cortical granules in the perivitelline space which hardens the zona pellucida so that other sperms cannot enter the ovum. This is called cortical reaction.

Only one sperm enters the ovum and loses its tail.

Hence not all sperms entering the female reproductive tract can enter inside the ovum.