The study of gametogenesis provides valuable information about the formation of gametes. Prepared slides were used to observe the anatomy and physiology of the processes of oogenesis and spermatogenesis. Each prepared slide from the mammalian depicted all the stages that occur in the male and female during the birth of the gametes. The eggs and the sperm provide both the blue print and the raw material from which the embryo is formed. Both classes of gametes make an equal contribution to the nucleus of the zygote, each providing a haploid genome.
In the male, meiosis precedes sex cell differentiation. A single spermatagonium enters the first meiotic division as a primary spermatocyte. This division produces two secondary spermatocytes, each of which divides to form to haploid spermatids. Each spermatid than differentiates by spermiogenesis into a spermatazoan by the elaboration of structural and functional specializations that enable the sperm to fertilize the egg. Consequently four haploid sperm result from each diploid spermatogonium. The utilization of all four haploid cells in the male is significant because the testis must produce millions of sperms simultaneously.
In contrast to the situation in the male, germ cell differentiation in the female may occur early in meiosis. It is also important to keep in mind the difference in the number of sex cells produced in the male and the female. Each of the meiotic divisions in the female is uneven, producing only one full sized cell. During the first meiotic division, the primary oocyte divides to produce small polar body and one secondary oocyte. The latter enters the second meiotic division to produce the second polar body and the haploid ovum, which is the only functional sex cell to result from meiotic reduction from an oogonium.
The germ line is the link that provides the survival of species. Each generation of sexually reproducing organisms is dependent upon the germ line of its predecessors for its existence.