Spermatogenesis - Gametogenesis
The procedure of maturation of spermatogonia into sperms starts at puberty (about 14 years) and continues into old age. The spermatogonia that lie dormant in the testis since the foetal period begin to increase in number at puberty. After various mitotic divisions the spermatogonia transform into primary spermatocytes which are one of the largest germ cells in the tubules. Each of these primary spermatocytes goes through reduction division to form 2 haploid secondary spermatocytes. Subsequently, these go through a 2nd reduction division forming four haploid spermatids. The spermatids slowly transform into four mature sperms by a general processes of differentiation known as spermiogenesis. This whole process of spermatogenesis takes approximately 64 days. The mature sperm is a free swimming actively mobile cell consisting of head and a tail. The anterior two thirds of the nucleus in the head is covered through acrosome, an organelle that contains enzymes that help the sperms to penetrate the outer covering and membranes of the ovum.