With the help of a schematic labelled diagram, trace the development of mature spermatozoa in a human male.

Explanation

Spermatogenesis is the process of formation of spermatozoa (sperms) in the testes which originate from the Primordial Germ Cells (PGCs). The process of spermatogenesis initiates at puberty and continues even in old age.
It includes the following four stages
(i) Multiplication phase During this phase, the undifferentiated germ cells present in the seminiferous tubules of the testes known as spermatogonia or sperm mother cells increase in number by repeated mitotic divisions so that the newly formed spermatogonium possesses the same number of chromosomes.
(ii) Growth phase It gives rise to spermatocytes. Each spermatogonium accumulates large amount of nutrition and chromatin material. It is now known as primary spermatocyte which is diploid in number and contains . 46 chromosomes.

(iii) Maturation phase of formation of spermatids A primary spermatocyte undergoes first meiotic division leading to two equal haploid cells called secondary spermatocytes which contain only 23 chromosomes each .
The secondary spermatocytes undergo the second meiotic division to produce four equal haploid spermatids .
(iv) Differentiation phase The spermatids further are transformed into spermatozoa by the process called spermiogenesis .
During spermatogenesis , the germ cells are closely associated with Sortoli cells . Sperm heads become embedded in the Sertoli cells which provide mechanical support , protection and nourishment to the developing spermatozoa and are finally released from the seminiferous tubules by the process called spermiation .