The Testicle

Testicular cancer is cancer of the testicles. But while you may know where they are and you may know a little bit about what they do, chances are that you don't know what is going on inside of them. This page is intended to be a very brief overview of the anatomy and function of the testicle.

Functions of the Testicle

The testicles (also called testes or gonads) are the male sex glands. They are located behind the penis in a pouch of skin called the scrotum. The testicles produce sperm and testosterone. The testicles are located outside the body because sperm develop best at a temperature several degrees cooler than normal internal body temperature.

Inside the testicle are tiny tubes called seminiferous tubules, where sperm are made. The developing sperm cells are supported by Sertoli cells, which help nourish and regulate them as they mature.

Sperm production takes about two months. The immature sperm then move into the epididymis, the coiled tube behind the testicle, where they finish maturing and are stored until ejaculation. During ejaculation they travel through the vas deferens and mix with fluids from the prostate and seminal vesicles to form semen.

Scattered between the seminiferous tubules are Leydig cells, which produce testosterone. Testosterone is important for sexual development and function, sex drive, muscle and bone health, body and facial hair, and many other functions. If testosterone becomes too low, symptoms can include reduced sex drive, fatigue, hot flashes, mood changes, loss of muscle, and thinning of the bones.

When we talk about testicular cancer, we are normally talking about cancer of the germ cells. Tumors can also arise from Leydig cells, Sertoli cells and other tissues in or around the testicle. These tumors are much less common, and most Leydig and Sertoli cell tumors are benign, although a small number can be malignant.