The testicles

The testicles (testes) are part of a man’s reproductive system. A man has 2 testicles. Each testicle is egg-shaped and about 5 cm long. The testicles are covered by a sac of skin called the scrotum. The scrotum hangs below the penis, between the legs. The testicles make sperm. They also make testosterone, which is a male sex hormone.

Each testicle is covered by tough, fibrous layers of tissue called the tunica. The outer layer is called the tunica vaginalis and the inner layer is called the tunica albuginea.

The testicle is divided into parts called lobules. Each lobule contains tiny U-shaped tubes called seminiferous tubules. There are about 800 seminiferous tubules tightly coiled within each testicle.

The seminiferous tubules open into a series of uncoiled, interconnected channels called the rete testis. Ducts, or tubes, connect the rete testis to a tightly coiled tube called the epididymis. The epididymis joins to a long, large duct called the vas deferens.

Each testicle is held in the scrotum by a spermatic cord. Each spermatic cord is made of tough connective tissue and muscle. It contains the vas deferens, blood vessels, lymph vessels and nerves.

Lymph fluid travels through vessels in the spermatic cord and drains from the testicles into several groups of lymph nodes at the back of the abdomen. These lymph nodes are called the retroperitoneal lymph nodes.