Testes are the primary reproductive organs in man (males). The function is to make the male sex cell or male gametes called sperms and also to make the male sex hormone called testosterone. These are outside the abdominal cavity of the body, because the sperm formation requires a lower temperature. Being outside the abdominal cavity the temperature of scrotum is about 3" C lower than the temperature inside the body. In this way testes provide appropriate temperature for formation of sperms. The male sex hormone testosterone is responsible for bringing about changes in appearance seen in boys at the time of puberty.