Question

The spermiogenesis involves all of the following except
A. Formation of mitochondrial sheath
B. Formation of proximal and distal centrioles
C. Formation of acrosomes
D. Shortening of sperm

Answer 1

Hint: During spermiogenesis, flagellum formation takes place in the sperm. The sperm cell develops the sperm tail.

Complete answer:
- Spermatogenesis is the mechanism by which haploid sperm cells in the testis seminiferous tubules grow from the germ cells. This mechanism begins with the mitotic division of the stem cells situated near the lower membrane of the tubules. These cells are known as spermatogonial stem cells.
- The entire spermatogenesis process can be broken down into many distinct stages, each leading to a specific type of cell in humans. The major stages of spermatogenesis are spermatocytogenesis, spermatogenesis and spermiogenesis.
- The division of spermatids into sperm cells is termed as spermiogenesis. During spermiogenesis, spermatid is transferred to mature sperm cells. It's the last step of spermatogenesis. There are four processes in this phase, namely nuclear condensation, acrosome formation, flagellum formation and cytoplasm reduction. The nucleus gets smaller and denser during nuclear condensation.
- The nucleus and the acrosome form the sperm head. The cap (acrosome) containing lysosomal enzymes are produced during the development of acrosomes. It plays a significant function in the penetration of the pellucid zone of the egg.
- In the neck region, proximal and distal centrioles are developed during flagellum development and the mitochondrial sheath is formed in the midpiece region. Unnecessary cytoplasmic contents are eliminated during cytoplasm reduction.

Thus, the correct answer is option D. i.e., Shortening of sperm.

Note: Spermatogenesis occurs in the lower portion of the seminiferous tubules and gradually the cells go deeper into the tubes and travels down them until the mature sperm enters the lumen where mature sperm cells are stored. The separation occurs asynchronously; if the tube is sliced transversely, various maturation states might be identified.