NAME THE PROCESS OF FORMATION OF SPERMATIDS FROM SPERMATOGONIA  AND SPERMATOZOA FROM SPERMATIDS. EXPLAIN IN DETAIL WITH THE HELP OF SIAGRAM SHOWING DFFERENT PHASES LIKE DIFFERENTIATION, MULTIPLICAYION, GROWTH PHASE

The process of formation of spermatids from spermatogonia and spermatozoa from spermatids is called spermatogenesis.

 

Multiplication Phase

 1.The undifferentiated primordial germ cells divide several times by mitosis to produce a large number of spermatogonia(2n).

 2.Spermatogonia are of two types—A and B.

 3.Type A spermatogonia act as stem cells which divide and produce more spermatogonia,while type B spermatogonia are the precursors of sperms.

 

 Growth Phase

 

Each type B spermatogonia actively grows to form a larger primary spermatocyte by obtaining nourishment from nursing cells.

 

 Maturation Phase

 1.Each primary spermatocyte undergoes two successive divisions called maturation divisions.

2.The first division is reductional or meiotic division where each primary spermatocyte divides into two haploid daughter cells called secondary spermatocytes.

3.Both secondary spermatocytes undergo a second maturation division to form four haploid spermatids from a single primary spermatocyte.