testosterone

Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles,[1] birds,[2] and other vertebrates. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands. It is the principal male sex hormone and an anabolic steroid.

In men, testosterone plays a key role in the development of male reproductive tissues such as the testis and prostate as well as promoting secondary sexual characteristics such as increased muscle and bone mass and hair growth.[3] In addition, testosterone is essential for health and well-being[4] as well as the prevention of osteoporosis.[5][...]
http://en.wikipedia.org/wiki/Testosterone

http://en.wikipedia.org/wiki/Stereotype_%28printing%29