testicle
Meaning of testicle: Sperm production needs a temperature the abdomen cannot provide, which is why these glands hang outside the body in a thin skinned pouch.
Definition of testicle
A testicle is one of the two oval glands held in the scrotum, the pouch of skin behind the penis. Each contains tightly coiled tubules in which sperm are made, along with a separate population of cells that produce testosterone and release it into the blood. The paired glands are therefore both a reproductive organ and a hormone producing one.
What is inside a testicle?
The bulk of the organ is tubing. Hundreds of tightly coiled seminiferous tubules, each far longer than the gland that holds them, are packed into compartments separated by fibrous partitions. Sperm develop within the walls of these tubules, moving from the outer edge toward the central channel as they mature over a period of weeks. Supporting cells lining the tubules nurse them through the process and form a barrier that seals the developing sperm off from the bloodstream and from the immune system, which would otherwise treat them as foreign. Between the tubules sit clusters of a different cell type, and these are the ones that make testosterone under direction from a pituitary signal.
Why does it sit outside the body?
Sperm production works only slightly below core temperature. The scrotum holds the glands away from the trunk, its thin skin loses heat readily, and a sheet of muscle in the scrotal wall along with another attached to the cord above pull the glands closer to the body in the cold and let them hang lower in the heat. Blood arriving through the artery is cooled on the way in by the network of veins wrapped around it heading out. The whole arrangement works as a temperature regulator, which is why a gland that never descends stays warmer than it should and produces poorly.
What commonly goes wrong?
| Condition | What it is |
|---|---|
| Undescended testicle | The gland has not reached the scrotum by the expected age; a retractile one has descended but is pulled up temporarily by a reflex |
| Torsion | The cord twists and cuts off the blood supply, causing sudden severe pain and treated as a surgical emergency |
| Epididymitis | Inflammation or infection of the epididymis, the coiled tube where sperm mature before ejaculation |
| Varicocele | Enlarged veins draining the gland, sometimes affecting fertility |
| Hydrocele | Fluid collecting in the sac around the gland, giving painless swelling |
Also known as
Used in a sentence
Physical examination included palpation of both testicles to assess for swelling or tenderness.
Good to know
An undescended testicle, one that has not moved into the scrotum by the expected time, is distinguished from a retractile testicle, which has descended normally but can temporarily pull upward due to a reflex muscle response.
Word origin
Where “testicle” comes from
Formed from Latin testiculus, a diminutive of testis, meaning witness.