Which part of the sperm help in its entry into the cytoplasm of the ovum ?

Acrosome

The correct answer is Option (4): Acrosome

The part of the sperm that assists in its entry into the cytoplasm of the ovum is the Acrosome.

Acrosome is the cap like structure present on the anterior half of the head of the sperm. During fertilisation, the nucleus of sperm fuses with the nucleus of egg resulting in the formation of a diploid zygote. In order to fuse with the egg, the sperm has to penetrate the envelopes surrounding the egg. The acrosome of the sperm releases enzymes that help to penetrate the membranes of the egg. This is called acrosome reaction.The secretions of the acrosome help the sperm enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane. This induces the completion of the meiotic division of the secondary oocyte.