NCERT · Class 12 · Biology · Human ReproductionDraw a neat and labeled diagram of the human sperm and briefly explain the functions of its different parts.

A human sperm is a microscopic, motile structure composed of a head, neck, middle piece, and tail.

1. Head: The head contains an elongated haploid nucleus. The anterior portion of the head is covered by a cap-like structure called the acrosome. The acrosome is filled with hydrolytic enzymes that help in fertilizing the ovum by breaking through its protective layers.
2. Neck: It contains the proximal centriole, which is essential for the first cleavage division of the zygote after fertilization, and the distal centriole that gives rise to the axial filament of the tail.
3. Middle Piece: It possesses numerous mitochondria. These mitochondria act as the powerhouse of the sperm, generating energy (ATP) in the form of motility for the tail to move and swim towards the ovum.
4. Tail: It is a long, whip-like flagellum that facilitates the active swimming of the sperm in the female reproductive tract to reach the site of fertilization.