What are testicles for?

Dear Alice,

Do the testicles store and/or produce sperm? If not, what are they for?

— Ball-sy

Dear Ball-sy,

Ah, the family jewels. Testicles produce sperm and the hormone testosterone. Sperm grows in the seminiferous tubules, which are coiled tubes located in the testicles. The sperm is stored and matures in the epididymis, long, coiled tubes on the back of each testicle. The testicles hang in a sack, called the scrotum, that sits outside of the body because sperm needs to be stored at a temperature that's slightly below that of the body.

Just as penis size varies from one person to the next, there's a wide range in testicle size as a proportion of the human body. In other words, some balls are big while others are small! In addition, no one is completely symmetrical. It's perfectly normal for one testical to be larger or smaller than the other, and for the two to hang at different angles or heights.

Performing regular testicular self-examinations (TSE) can help you get and stay familiar with your anatomy. A TSE can best be done in the shower because the hot water relaxes the scrotum and soap reduces friction while examining. Here are some guidelines for performing testicular self-exam:

  • Turn each testicle between the thumb and forefinger — feel for a firm, round surface.
  • Examine the rest of the scrotum contents and feel for changes.
  • If you feel a lump on the testicle surface, even if it's not painful, it's wise to see a health care provider.

If you notice a significant change to the size of one the testicles, or experience soreness, sensitivity, or bumps, it's wise to check in with a health care provider. 

Last updated Jun 17, 2022
Originally published Dec 11, 1995

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