Testicles

Overview

What is a testicle?

A testicle (pronounced “teh-stuh-kl”) is part of the anatomy of men and people assigned male at birth (AMAB). Generally, you’ll have two testicles. These body parts make sperm and hormones.

Other names for your testicles are male gonads or testes (pronounced “teh-steez”). One testicle is called a testis. There are other more casual names for testicles that you might hear or even use yourself, including “balls,” “nuts” and “cojones.”

Function

What do the testicles do?

The testicles make sperm and sex hormones, particularly testosterone.

How do the testicles make sperm?

Testicles are about two degrees Celsius lower in temperature than the rest of your body. Cooler temperatures are better for making sperm, a process called spermatogenesis. In each of the testes, the process happens in tubes called seminiferous tubules. There are a surprising number of tubes in each testis — about 700.

It takes about 74 days for sperm cells to mature. The immature cells get the blood and nutrients they need in the tubules. From there, they’re pushed along to the epididymis, another type of tube that runs along the back side of your testicle. The epididymis connects to the vas deferens, which is the tube that lets sperm leave your body through your penis.

What are the hormones made by the testes?

The testes make hormones like testosterone in the Leydig cells. Testosterone is a hormone that causes people to have deeper voices, stronger muscles and body hair. The testes also make these other hormones:

  • Inhibin B: Serum levels of this protein are related to testicular volume and sperm counts in adults.
  • Anti-Mullerian hormone: This hormone is important to the development of internal male reproductive organs.
  • Insulin-like factor 3: This hormone helps testicles descend into the scrotum from the abdomen and to continue to develop in the scrotum.
  • Estradiol: This hormone is important in making sperm.

Anatomy

Where are the testicles located?

Your testicles are located underneath your penis. They’re enclosed in a pouch of skin called the scrotum. Generally, you’ll have one testicle to the right and one testicle to the left of your penis.

Your testicles are connected to the inside of your body by a cord called the spermatic cord. Each cord contains nerves and blood vessels. The cords also contain the vas deferens, which are the tubes that move sperm to your penis, so it can leave your body in semen.

What do the testicles look like?

Your testicles aren’t visible because they’re located inside your scrotum. However, their outlines are visible, and you can feel them. Testicles have been described as being like large olives, small eggs or walnuts.

How big are testicles?

There’s no exact size for testicles. In fact, one of your testicles may be a little bit bigger than the other one. One testicle might be a little lower than the other. An adult testicle may range from half an inch (15 mL) to 1.5 inches (35 mL) or more. One comparison says the normal range goes from the size of a bird egg to the size of a small chicken egg.

Conditions and Disorders

What are the common conditions and disorders that affect this body system or organ?

Many testicle-related diseases are found in children, but not all. Here are some conditions that could affect your testicles:

  • Hypogonadism: Your testicles don’t produce enough of the hormones you need.
  • Klinefelter syndrome: This genetic condition happens when a person is born with two copies of the X chromosome and one copy of the Y chromosome.
  • Infertility: This refers to being unable to impregnate a partner. Your testicles may not produce any — or enough — sperm, or they might not be able to release the sperm.
  • Cryptorchidism: This condition, also called undescended testicles, refers to testicles that don’t drop into your scrotum when they should.
  • Epididymitis: This condition refers to an inflammation of the epididymis.
  • Spermatocele: This is another name for a cyst that grows above or behind a testis.
  • Testicular torsion: This medical emergency happens when a testis becomes twisted, and the blood supply is cut off. You need to get help right away.
  • Testicular cancer: This condition is the most common cancer in men and people assigned male at birth (AMAB) who are between the ages of 20 and 35 years old.

Your testicles can be damaged by physical trauma, including motor vehicle accidents, falls or fights.

Contact your healthcare provider if you develop these signs or symptoms:

  • Pain in your scrotum and/or testicles.
  • A lump or swelling on your testicle.
  • Discoloration of the skin on your scrotum.
  • An abnormal feeling of warmth in the area.
  • Blood in your semen.
  • Pain in your lower abdomen.

What are some common tests to check the health of your testicles?

Your healthcare provider will begin by going over your medical history and your current symptoms. The tests they order will depend on what they think they’ll find. You may have:

  • A physical examination of your testes.
  • Blood tests to evaluate hormone levels.
  • Urine tests to check for infection or other diseases.
  • A light test to distinguish a solid growth from a fluid-filled cyst.
  • An ultrasound of your scrotum and testicles to evaluate lumps.

Your healthcare provider will treat testicular disorders with a variety of therapies. Depending on the testicular disorder, treatments may include:

  • Self-care treatments, like using over-the-counter pain relievers, ice to relieve swelling or scrotal support garments.
  • Medications, such as antibiotics or testosterone supplements.
  • Surgeries, such as orchiopexy to move undescended testicles to the scrotum, and procedures to untwist testicles or remove benign or cancerous cysts.
  • Radiation therapy.
  • Chemotherapy.

Care

How do I keep my testicles healthy?

Here are some tips to keep your testicles healthy:

  • Wear protection. If you play sports or participate in other vigorous activities, wear an athletic supporter (a jockstrap).
  • Keep clean. Wash yourself thoroughly and often. Wear clean underwear and clothing.
  • Practice safe sex.
  • Examine your testicles regularly. Become familiar with the way they’re shaped, feel and look. Be aware of any changes, like lumps or swelling. If something seems wrong, contact your healthcare provider.

Frequently Asked Questions

Can a person without a testicle make another person pregnant?

One testicle can product enough sperm to get another person pregnant. If your healthcare provider must remove both testicles because you have cancer or an injury, you may be able to bank frozen sperm that could be used to impregnate a partner.

A note from Cleveland Clinic

Your testicles are important parts of your anatomy. They’re related to your sexuality and your ability to reproduce. You should become familiar with how they feel and look when they’re healthy. Pay attention to any change. Contact your healthcare provider if you notice any lumps or other changes.

Last reviewed by a Cleveland Clinic medical professional on 08/09/2022.

References

  • Department of Health, State Government of Victoria, Australia. Testicular self-examination. (https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/testicular-self-examination) Accessed 8/9/2022.
  • Encyclopedia Britannica. Many articles reviewed for this article. Spermatogenesis. (https://www.britannica.com/science/spermatogenesis) Accessed 8/9/2022.
  • NHS. What should my testicles look and feel like? (https://www.nhs.uk/common-health-questions/mens-health/what-should-my-testicles-look-and-feel-like) Accessed 8/9/2022.
  • Society for Endocrinology. Testes. (https://www.yourhormones.info/glands/testes/) Accessed 8/9/2022.
  • The Male Genitalia and Reproductive System. In: Suneja M, Szot JF, LeBlond RF, et al., eds. _DeGowin’s Diagnostic Examination. _11th ed. McGraw Hill; 2020. Accessed 8/9/2022.

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