Male sex organs

Male Sex Organs
From the outside, the male has two visible sex organs, the testes and penis. The testes (singular: testis) are the primary male sexual organs in that they make sperm and produce testosterone. The sperm cell is the male sex cell (gamete). Testosterone is the hormone that causes male secondary sex characteristics such as facial and pubic hair, thickened vocal cords and developed muscles.

The testes are housed outside of the main part of the male's body, in a sac called the scrotum. This location is important because in order for the sperm to develop properly, they must be kept at a slightly lower temperature (95 to 97 degrees Fahrenheit, 35 to 36 degrees Celsius) than normal body temperature (98.6 F, 37 C).

The immature sperm travel from each testis to a coiled tube on the outer surface of each testis called the epididymis, where they mature in about 20 days. The sperm exit the body through the penis.

The penis is made of soft, spongy tissue (see How Viagra Works for details). When engorged with blood during sexual excitation and intercourse, the spongy tissue stiffens and causes the penis to become erect, which is important for the penis's main function -- to place the sperm inside the female.