The male gonads are already present in the body at birth, but do not produce sperm until adolescence. When puberty sets in, at about the age of 13, the testes, penis and scrotum begin to grow.
Maturity is reached when the testes produce functional sperm.
The testes are also a type of endocrine gland that produce male sex hormones, such as testosterone. Sperm, or spermatazoa, are produced in the testes, which are linked through a series of vessels to the penis. Semen is a milky sperm-carrying fluid produced by the prostate gland and the seminal vesicles. The liquid is there to dilute the sperm so they can move and also to nourish and activate them for sexual reproduction. During ejaculation, a man will produce between 2 and 5 millilitres of semen that contains between 50 and 130 million sperm per millilitre.