Gametogenesis studies the process of gamete formation. Ova (sing: ovum) and sperm are gametes. The production of these special sex cells involves the process of meiosis. Meiosis is also called reduction_division, because it involves reducing the total number of chromosomes in a single cell by exactly one half. In humans, this means a reduction from 46 to 23 chromosomes. The full complement of chromosomes in a regular somatic_cell (body cell) is termed the diploid number. The reduced number of chromosomes present in gametes is termed the haploid number.
Meiosis occurs in organs known as gonads. Gonads produce two products: gametes and sex hormones. Only gonadal cells destined to become eggs and sperm undergo the process of meiosis.
The testes (sing: testis) are the gonads of the male. Each testis is divided into lobules, and each lobule contains one highly coiled seminiferous_tubule. These tubules are the sites of sperm cell production.
Seminiferous tubules consist of several types of cells, including sustenocytes and interstitial_endocrine cells. Sustenocytes are also known as sustentacular, nurse, or Sertoli_cells, and interstitial endocrine cells are often referred to as just interstitial cells or Leydig_cells. The sustentocytes support and nourish developing sperm, and the interstitial endocrine cells produce male hormones.