The testicles

The testicles produce sperm and the hormone testosterone. They are the main part of the male reproductive system.

Anatomy of the testicles

The testicles are 2 oval-shaped organs inside the scrotum. The scrotum is a pouch of skin behind the penis. The testicles hang below the penis. They are sometimes called the testes. They are the main part of the male reproductive system. Testicles produce sperm. Sperm can fertilise a female egg to make a baby.

The structure of the testicle 

The structure of the testicle
Image: The structure of the testicle

Sperm travels from the collecting tubules inside the testicle to a coiled tube called the epididymis. The epididymis feels like a soft swelling at the back of the testicle. The tube becomes a wider tube called the vas deferens, which is part of the spermatic cord.

This then joins a shorter tube, called the ejaculatory duct (see below). The ejaculatory duct connects to a tube called the urethra, which goes from the bladder to the end of the penis.

Sperm mixes with fluid from the prostate and the seminal vesicles. These are glands that sit just under the bladder. The sperm and fluid are forced (ejaculated) along the urethra and out from the penis. The ejaculated fluid and sperm are called semen.

The male reproductive system

The male reproductive system
Related pages


The testicles also make the hormone testosterone. Hormones are chemical messengers that help control different functions in our bodies.

Testosterone helps with:

  • sex drive (libido)
  • getting an erection
  • having a deep voice
  • facial and body hair
  • muscle development.

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    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr Ursula McGovern, Consultant Medical Oncologist.

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We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

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Date reviewed

Reviewed: 01 May 2022
Next review: 01 May 2025
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.