Questions & Answers

The number of chromosomes in the spermatids of a man
a. 48
b. 23
c. 24
d. 46

Answer Verified Verified
Hint: The spermatids of a man are the haploid cells. They contain half the number of chromosomes that are present in the spermatogonia (from which these spermatids are formed).

Complete answer:
To solve the question we must know the complete process of spermatogenesis and the various number of chromosomes that are present inside the cell in the different stages before they finally become the spermatozoa or the sperms.

Spermatogenesis is the process of the formation of sperms inside the male reproductive system. The process starts with the mitotic division of the spermatogonia. The spermatogonium is a diploid cell and contains 46 chromosomes (=23 pairs). The mitotic division of the spermatogonia gives rise to a number of primary spermatocytes. They are diploid cells because the mitotic division is an equational division, and the numbers of chromosomes in the cell remain the same before and after the division. These primary spermatocytes then undergo meiosis to further give rise to a number of secondary spermatocytes. Since meiosis is the reduction division, hence the numbers of chromosomes that are passed on in the secondary spermatocytes are halved i.e. now the secondary spermatocytes contain 23 chromosomes each. These undergo a second meiotic division to produce haploid spermatids. Finally, these spermatids undergo a process of spermiogenesis to form the male gametes, or what we commonly call it, sperms.

Since now we know that spermatids are the products of the second meiotic division, hence the number of chromosomes present in the spermatids of a man is 23 chromosomes.

The second meiotic division is similar to the mitotic division and the entire process of the second meiotic division should not be confused with the first meiotic division. Further, in the first meiotic division, the chromosome numbers are halved whereas when the second meiotic happens only the cells multiply the number of chromosomes remains the same.