Testosterone, the principal male sex hormone, is produced in the testes.

Testosterone, an androgen, is necessary for the development of external genitals in the male fetus. In addition, increased levels of testosterone in males during puberty trigger the development of secondary sexual characteristics such as facial hair and a deepening voice. If the testes are not able to produce adequate amounts of testosterone, puberty does not occur. The testes may be damaged by injury, illness (mumps), chemotherapy, or radiation therapy. In Klinefelter's syndrome, which occurs in one in 600 males, the testes do not develop normally. In order to induce and maintain male secondary sex characteristics, adolescents with Klinefelter's and other conditions that prevent the testes from producing adequate amounts of testosterone must be treated with synthetic testosterone.

For Further Study

Books

Avraham, Regina. The Reproductive System. New York: Chelsea House, 1991.