At sexual maturity the germ cells in human male divide several times by mitosis to produce a large number of spermatogonia. In growth phase each spermatogonium actively grows to a larger primary spermatocyte by obtaining a nourishment from the nurshing cells. In maturation phase each primary spermatocyte undergoes two successive divisions called maturation divisions. The primary spermatocyte undergoes first maturation division (meiotic) to producing two haploid daughter cells called secondary spermatocytes. Both secondary spermatocytes undergo second maturation division to form four haploid spermatids. The transformation of spermatids into spermatozoa is called spermiogenesis or spermateliosis.