Testicles are oval-shaped organs which are located in the scrotum, just behind the penis and right in front of the anus on male humans. The main function of the testes is producing and storing sperm. They also produce testosterone and other male hormones called androgens. Androgens control how the male reproductive system grows and the development of masculine body features such as beards and a deep voice. Testosterone is the most common form of androgen. It is responsible for the growth of male genitals and sperm production.