Question

Explain spermatogenesis in detail.

Answer 1

Spermatogenesis is the formation of spermatozoa from germ cells in the seminiferous tubules of the testes. It begins at puberty. Sertoli cells nourish the developing germ cells.

1. Multiplication phase: Diploid spermatogonia divide repeatedly by mitosis.
2. Growth phase: Some spermatogonia grow and become primary spermatocytes, each with 2n=46 chromosomes.
3. Maturation phase: Each primary spermatocyte undergoes meiosis I to form two haploid secondary spermatocytes. Each undergoes meiosis II, producing four haploid spermatids, each with n=23 chromosomes.
4. Spermiogenesis: Each spermatid differentiates into a sperm, developing a head, middle piece and flagellum while losing excess cytoplasm.
5. Spermiation: Mature spermatozoa are released from Sertoli cells into the lumen of the seminiferous tubule. They then pass to the epididymis, where they mature and are stored.

Thus, one primary spermatocyte produces four haploid spermatozoa.