Testis

One of 2 male sexual organs, also called testicles, that produce sperm and the hormone testosterone. The testes develop in the fetus within the abdomen and usually descend into the scrotum by birth or within the next few months. Each testis contains seminiferous tubules that produce sperm. Cells between the seminiferous tubules produce testosterone. Each testis is suspended by the spermatic cord, composed of the vas deferens, blood vessels, and nerves. (See also testis, undescended.)