TESTES

n.

or testicles

Male reproductive organs (see reproductive system ).

Humans have two oval-shaped testes 1.5–2 in. (4–5 cm) long that produce sperm and androgens (mainly testosterone ), contained in a sac (scrotum) behind the penis . Each testis is divided into 200–400 lobes containing three to 10 very thin coiled tubes (seminiferous tubules) each, which produce the sperm and contract to expel them through a complex network of canals to another structure in the scrotum, the epididymis, for temporary storage. The cells in the testes are undeveloped in early childhood; at puberty they are stimulated by hormones to develop into fertile sperm cells.