Explain the phases of spermatogenesis in humans with the help of a diagram.
Spermatogenesis: Formation of sperms in testis is called as spermatogenesis. It involves the following steps:
(1) Multiplication phase: In this phase, the cells of generative layer divide and redivide to produce spermatogonia.
(2) Growth phase: In this phase, spermatogonia grows and then it is called as.spermatocytes.
(3) Maturation phase: In this phase metamorphosis occurs in the spermatids to produce a well-developed sperm which is divided into three parts:
(i) Head,
(ii) Neck
(iii) Tail.