The testis produces gametes i.e. sperms by the process of spermatogenesis. In testis the immature male germ cells (spermatogonia) produce sperms by spermatogenesis that begins at puberty age. The spermatogonia present on the inside wall of seminiferous tubules multiply by mitotic division and increase in numbers. Each spermatogonia is diploid and contain 46 chromosomes. Some of the spermatogonia called primary spermatocytes periodically undergo meiosis. A primary spermatocyte complete, the first meiotic division leading to formation of two equal haploid cells called secondary spermatocytes which have only 23 chromosomes each. The spermatocytes undergo the second meiotic division to produce four equal haploid spermatids. These spermatids are transformed into sperms/spermatozoa by the process called spermatogenesis.

Spermatogenesis starts at the age of puberty at which significant increase in the secretion of ganadotropin releasing hormone (GnRH) occurred. The increased level of GnRH acts at the anterior pitutary gland and stimulates secretion of two gonadotropins–Lutenising hormone (LH) and follicle stimulating hormone (FSH). LH acts at the leydig cells and stimulates synthesis and secretion of Androgenes. Androgenes, in turn, stimlate the process of sepermatogenesis. FSH acts on the sertoli cells and stimulates secretion of some factors which help in the process of spermatogenesis.