Testes serve as the site of spermatogenesis for the production of sperm. The endocrine cells present in the space between seminiferous tubules are termed as interstitial cells. They serve to secrete androgen, testosterone, which is responsible for the development of male secondary sexual characters. Ovaries serve as the site of egg production by oogenesis and secrete female sex hormones namely estrogen and progesterone for development of female secondary sexual characteristics.