Question

How many spermatids are formed by a primary spermatocyte?

Answer 1

Hint: Testis and ovaries are known to be primary sex organs because they produce gametes which are sperms and ovum respectively. The process by which the gametes are formed is called gametogenesis and in the case of males, it is known as spermatogenesis . The male germ cells that are present in testis are called spermatogonia which produce sperm.

Complete answer:
Spermatogenesis is the process of formation of sperm and it proceeds in four stages. Spermatocytogenesis - The spermatogonia which are present on the wall of the seminiferous tubules (present in testicular compartment) and they start dividing by mitotic divisions which does not includes reduction in chromosomes and thus is known as equational division but increase in number is still witnessed. The spermatogonia are diploid cells consisting of 46 chromosomes. Some of these cells undergo changes which are; they grow and increase their size by the accumulation of substances that are needed for nourishment and are known as primary spermatocytes which then succeed to the second stage, i.e. meiosis. Meiosis-I- It is a reductional division which involves reduction in chromosomes. The primary spermatocytes which are diploid cells with 46 chromosomes divide into daughter cells which are haploid cells with 23 chromosomes. Meiosis-II - This is very much similar to mitosis. It is an equational division. At the end of the division, we get secondary spermatocytes which are haploid.
So, one primary spermatocyte divides into two after meiosis-1, and finally after meiosis-2,it produces 4 haploid cells.

Additional information:
DNA content: - The spermatogonia starts dividing by the process of mitotic division so this indicates that the same number of chromosomes are transferred into daughter cells and hence the DNA content remains same as present in primary spermatocytes.
Note:
A mature sperm has usually developed a head, neck, middle piece and a tail. The plasma membrane covers the sperm. Head of the sperm contains cytoplasm and a nucleus (haploid). Although the anterior part of the head has a covering of acrosomes which are made up of Golgi bodies, the middle piece consists of mitochondria which provides energy for movement of the sperms.