The testicles are sometimes called the testes. They’re two small, oval-shaped organs, contained in a sac of skin called the scrotum, which hangs below the penis.
From puberty, the collecting tubules inside the testicles produce sperm, which can fertilise a female egg. The testicles are the main organs of the male reproductive system.
The tubules form a coiled tube called the epididymis. This feels like a soft swelling at the back of the testicle. The epididymis carries on to the outside of the testicle and widens to become the spermatic cord (vas deferens).
This joins to the ejaculatory duct where sperm is ejaculated out of the penis. Sperm is mixed with fluid from the prostate and seminal vesicles (small tubular glands near the prostate) before it is ejaculated from the penis. The ejaculated fluid and sperm are called semen.
The testicles also produce the hormone testosterone. Hormones are chemical messengers that help to control different activities in our bodies. Testosterone is responsible for:
your sex drive (libido)
getting an erection
having a deep voice
facial and body hair
Sometimes cancer cells from the testicle can spread to nearby lymph nodes (also known as glands). Lymph nodes are small and round, and there are lots of them throughout the body. They’re connected to each other by a network of tiny lymphatic vessels that carry a fluid called lymph, which contains cells that help us fight infection. This is a part of our immune system − the body’s natural defence against infection.
Cancer cells can be picked up by the lymph fluid and carried to lymph nodes in other parts of the body. Lymph vessels in your testicles carry fluid to a collection of lymph nodes at the back of your tummy (abdomen). These lymph nodes are called the retroperitoneal lymph nodes. They lie just behind your bowel and in front of your spine. You’ll have a scan (CT scan) to check if any of these nodes are larger than normal.