Spermatogenesis is the process by which immature male germ cells (spermatogonia) produce sperms in the testis. It begins at puberty due to increased secretion of gonadotropin releasing hormone (GnRH) from the hypothalamus.

The process occurs on the inside wall of seminiferous tubules where spermatogonia multiply by mitotic division, increasing their numbers. Each spermatogonium is diploid and contains 46 chromosomes. Some spermatogonia called primary spermatocytes periodically undergo meiosis.

A primary spermatocyte completes the first meiotic division (reduction division) to form two equal, haploid cells called secondary spermatocytes, each with only 23 chromosomes. These secondary spermatocytes undergo the second meiotic division to produce four equal, haploid spermatids.

The spermatids are transformed into spermatozoa (sperms) by a process called spermiogenesis. After spermiogenesis, sperm heads become embedded in the Sertoli cells, and are finally released from the seminiferous tubules by the process called spermiation.

Hormonal regulation involves LH acting on Leydig cells to stimulate androgen synthesis, which promotes spermatogenesis. FSH acts on Sertoli cells to secrete factors that help in spermiogenesis. A normal human sperm consists of a head, neck, middle piece, and tail.