The principal steroid secreted by testes is

Testosterone is the principal male sex hormone (androgen) that is produced by Leydig&;s cells of the testes in response to the luteinizing hormone secreted by the pituitary gland. Its chief function is to stimulate the development of the male reproductive organs, including the prostate, and the secondary sex characters, such as the beard. It encourages the growth of bone and muscle and helps maintain muscle strength.Ref; Ganong&;s review of medical physiology;24th edition; page no:-423