Question

Describe the events that lead to the formation of sperm - Spermatogenesis.

Answer 1

Spermatogenesis is the process of formation and maturation of reproductive cells in testes of male gametes.

So there is two major events in spermatogenesis.

1. Formation of spermatid and 2. Metamorphosis of spermatid.

1. Formation of spermatids again consist of 3 process

A. Multiplication= In this step the germ cell of the germinal epithelium lining the seminiferous tubules of testes are known as primary germ cells.

Durning multiplication phase primary germ cells multiply by mitosis. And there end product is known as spermatogonia. Each spermatogonia possses two set(2n) number of chromosomes.

B. Growth phase is now next phase in this as the name of this step explains the spermatogonia formed at the end of multiplication phase increases in size and attain maturity. Now the mature spermatogonia are called as primary spermatocytes .

C= maturation phase. In this step each primary spermatocyte divides by reduction division is termed as first reduction devision.( Reduction divison called because chromosome number reduced to half.) Now these are called secondary spermatocyte. Now these secondary spermatocyte undergoes second maturation division which is mitosis(equivalent division ) and result in formation of four spermatids.

2. Metamorphosis of spermatids = metamorphosis of spermatids is known as spermiogensis. The spermatids formed as result of maturation divison is typical animal cell contaning golgi body,mitochondria and centriole but one haploid set of chromosome. It is non motile.

So the changes are mainly with the reduction of weight and development of such structure that enable to move(tail.)

So the process of spermatogenesis results in the reduction of chromosome number in daughter cells which is exactly half of the parental cell. In the end four cells are formed from one spermatogonium.