Gametogenesis is the biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes. Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes, or by mitosis. In humans, gametogenesis is the process of division of diploid cells to produce new haploid cells. There are two types of gametes in humans: sperm and ovum. The process of sperm formation is called spermatogenesis, while the process of ovum formation is called oogenesis.
In males, spermatogenesis occurs in the testes. Immature germ cells or spermatogonia undergo mitotic division and their number increases. Primary spermatocytes undergo meiosis and produce haploid cells called secondary spermatocytes. These secondary spermatocytes undergo the second meiotic division to produce immature sperms or spermatids. These spermatids undergo spermiogenesis to transform into mature spermatozoa. Various hormones like GnRH, LH, FSH, and androgens are involved in stimulating spermatogenesis.
In females, oogenesis occurs in the ovary. Millions of oogonia or mother cells are formed during fetal development. These mother cells undergo meiotic cell division, which rests at the prophase-I and leads to the production of primary oocytes. Primary oocytes are arrested in the diplotene stage of prophase I until puberty. After puberty, one primary oocyte is selected each month to resume meiosis and complete the first meiotic division, producing a secondary oocyte and the first polar body. The secondary oocyte is ovulated and enters the fallopian tube. If fertilization occurs, the secondary oocyte completes the second meiotic division, producing a mature ovum and the second polar body.
Gametogenesis is an essential part of reproduction in mammals, through which the germ cell lineage undergoes a series of complex developmental processes. It is the process of forming mature germ cells and is integral to both an individuals and a species health and well-being.
