A steroid hormone--the most important of the androgens. First isolated from bull testes in 1935, testosterone is now manufactured for medical uses, including the treatment of forms of sterility in men that are caused by underdevelopment of the testes. Its use to promote muscular development among athletes is illegal.
The main androgen (male sex hormone). It is available as a variety of esters (testosterone enanthate <enanthate>, propionate, and undecanoate) for the treatment of underdevelopment of the testes or as replacement therapy in castrated men. It can also be used to prevent osteoporosis caused by lack of androgens. Testosterone is available, on prescription only, as capsules, an injection, a depot implant, or transdermal (skin) patches.
The most potent of the naturally occurring androgens. It is the primary testicular hormone in man, although small quantities are produced by the adrenal cortex of both males and females and by the ovaries in females. Testosterone accelerates tissue growth, causes maturation of the male genitals and the production of sperm, stimulates the development of the secondary sex characteristics including growth of facial, axillary and genital hair, voice changes, shifts in hairline (resulting in many cases in baldness), muscle development and the redistribution of body fat. It also plays an important role in aggression and dominance.