GAMETOGENESIS : SPERMATOGENESIS

Gametogenesis is the process of formation of gametes. It is divided into two parts - Spermatogenesis and Oogenesis. Spermatogenesis is the formation of sperms and Oogenesis is the formation of egg or ova.

Spermatogenesis is the process of formation of  sperms. A sperm is haploid and the cells from where it develops are diploid, so the process of formation of sperms need to pass through number of stages.The process of sperm formation starts when a boy reaches his puberty, generally around 15 years of age.

 The stages can be divided as follows:

1) Multiplication Phase

2)Growth Phase

3)Maturation Phase

4) Formation of Spermatozoa

In Multiplicative phase, the cells that are present in the seminiferous tubule under go division. This division is mitotic division and helps in increasing the number of cells without undergoing reduction in the constituents of the cell. It is Mitosis division. The male germ cells are also called as Spermatogonia.

After the multiplicative phase occurs the growth phase. Here in this phase Spermatogonia start growing. It accumulates huge amount of cytoplasm, DNA undergo replication and its size increases. They are now referred to as primary spermatocytes. The growth phase is also called as spermatocytogenesis. 

Next phase is the maturation phase, in this phase the spermatocytes undergo division. This division is meiotic division. Meiotic division is a reduction  division as from diploid condition the cells become haploid. Here from 23pairs of chromosome ie 46 number of chromosomes  become 23, so haploid. This leads to the formation of Spermatids.

Spermatids finally get transformed into spermatozoa. This process of formation of spermatozoa from spermatids is called Spermiogenesis.