The testes are two egg-shaped reproductive organs that are located in the scrotum of a male. They produce sperm, and the male hormone, testosterone. Both of these functions are controlled by other hormones produced by the pituitary gland. In mammals the testes are located outside the body to maintain a temperature slightly lower than body temperature, which is better for the sperm they produce. Nevertheless, when temperatures are colder, the testicles are drawn up closer to the body to maintain warmth. It is normal for one testis, usually the left one, to hang lower than the other; this is thought to be an evolutionary development to protect against the two testes bouncing against each other, which might damage them. The testosterone produced by the testes is used by the body to help bring about the changes in a boy's body that occur at puberty, such as growth of the penis and testes themselves, the emergence of facial and pubic hair, deepening of the voice, increase in muscle mass and strength, and increase in height. In an adult, testosterone helps maintain sex drive, sperm production, muscle and bone mass. |
