Gametocytes are eukaryotic germ line cells. They can undergo mitosis to form more gametocytes or undergo meiosis to form gametids. Male gametocytes are called spermatocytes and female gametocytes are called oocytes.

Spermatocytes are male gametocytes located in the seminiferous tubules of the testes. Primary spermatocytes are diploid and form when spermatogonia—immature germ cells—enter into mitosis. Primary spermatocytes can then enter meiosis and produce haploid secondary spermatocytes after meiosis I.

Spermatogonia are diploid undifferentiated male germ cells located in the seminiferous tubules of the testes. Spermatogonia are important in the process of spermatogenesis; they turn into primary spermatocytes via growth and maturation.

Mature sperm cells that are haploid, motile, and produced during spermatogenesis are called spermatozoa. Spermatids are haploid; however, they are immature. Spermatids will turn into spermatozoa once they mature.

Spermatozoa are stored in the epididymis prior to ejaculation. Prior to entering the epididymis, spermatozoa are immotile; however, as they travel through the epididymis the cells mature and gain motility.

Spermiogenesis is the final stage of spermatogenesis. In the process of spermiogenesis, spermatids develop into spermatozoa and form axoneme—the internal structure of the spermatozoa tails. It develops by way of microtubule growth from a single centriole that constructs the internal structure of the sperm tail. Mature spermatozoa have axonemes comprised of nine outer microtubule doublets and two central microtubules. These structures aid in motility.

Spermiogenesis is the final stage of spermatogenesis. In mature spermatozoa, the acrosome is the head of the cell and, in humans, contains digestive enzymes for ovum penetration. The acrosome develops during spermiogenesis when the Golgi apparatus surrounds the nucleus. 

Mitochondria cluster around the axoneme during spermiogenesis. They supply the energy needed for sperm movement, which is achieved through movement of the flagellum.

There is a high concentration of testosterone within the seminiferous tubules. The secretion of androgen-binding protein by Sertoli cells concentrates testosterone around cells undergoing spermiogenesis, The testosterone aids in the process of sperm maturation by removing excess organelles from the developing spermatozoa. 

The seminiferous tubules and developing spermatozoa within them are temperature-sensitive; they cannot tolerate high temperatures—including the temperature of the human body. In order to manage this, the testes are located outside of the human body in a sac of skin called the scrotum. This lowers the temperature of the seminiferous tubules to optimal levels.