Definition of Testis

Testis: The testis (or testicle) is the male sex gland. A pair of testes are located behind the penis in a pouch of skin called the scrotum.

The testes have two functions: one in regard to sperm and the other in regard to hormones. The testes produce and store sperm. The testes are also the body's main source of male hormones (testosterone) which control the development of the reproductive organs and other male characteristics, such as body and facial hair, low voice, and wide shoulders.

The word "testis" is a Latin word that means "witness." In ancient times, a person providing testimony might validate it by holding the scrotum, his or another man's. "And the servant put his hand under the thigh of Abraham his master, and sware to him concerning the matter." (Genesis 24:9)