Testosterone is the principal male sex hormone. While males produce testosterone in the testes, females produce small amounts of testosterone in the ovaries. Testosterone is necessary for various sexual functions, as well as protein synthesis and muscular development. Testosterone is responsible for development of the male genitalia in the womb, and is necessary for growth of the penis and testes during puberty. Secondary characteristics such as facial hair, pubic hair and a deepening voice also depend on testosterone. GROWTH OF BODY Testosterone helps males grow taller and more muscular during puberty. Testosterone also helps maintain muscle and bone strength in adulthood, and can have an effect on hair growth. SEX DRIVE Testosterone assists the testes in producing sperm, and helps keep a man's sex drive alive and well. If levels of testosterone in the body are low, men can experience a decreased desire to have sex, low sperm count, impotence or erectile...
Great article as usual! 
