testis

n.; pl. testes

either of the pair of male sex organs that produce spermatozoa and secrete the male sex hormone androgen under the control of gonadotrophins from the pituitary gland. The testes of the fetus form within the abdomen but descend into the scrotum in order to maintain a lower temperature that favours the production and storage of spermatozoa. The bulk of the testis is made up of long convoluted seminiferous tubules, in which the spermatozoa develop (see spermatogenesis). The tubules also contain Sertoli cells, which may nourish developing sperm cells. Spermatozoa pass from the testis to the epididymis to complete their development. The interstitial (Leydig) cells, between the tubules, are the major producers of androgens.