The testicles (also known as the "testes") are two small organs found inside the scrotum, part of the male reproductive system. The testicles are responsible for a number of essential functions, including the production of sperm and testosterone. Each testicle consists of a series of small tubes that are responsible for producing and storing sperm until it matures.
The testicles, also known as the testes, are sex glands that play an important role in the male reproductive system. Physically, the testicles take the form of two egg-shaped organs that are located in a small sac of skin called the scrotum.
The scrotum is an external organ that hangs in front of the pelvic region under the penis. For people born with testes, development of the testicles begins deep in the abdomen while they’re still in utero. The testicles will then descend down through the abdomen and into the scrotum sometime within the first few years after birth. There are a number of reasons why it's important for the testicles to descend, one being that the testicles need to stay cooler than body temperature to fully function.
The testicles are where spermatogenesis occurs. Millions of immature sperm are created each day in the testicles, starting in the seminiferous tubules. That immature sperm is sent to the epididymis and stored for several days to mature. When ejaculation occurs, sperm is expelled from the epididymis into the vas deferens and eventually makes its way out of the ejaculatory duct, where sperm meets seminal fluid.
Testosterone is a hormone that is responsible for the development of sex organs like the penis and other physical characteristics like body hair. Testosterone also contributes to bone and muscle growth and the formation of blood cells.
Studies have found a correlation between testicular size and sperm density. While some research suggests that people with larger testicles produce more sperm, that doesn't necessarily mean that people with smaller-than-average testicles are infertile. In fact, they may produce just as much sperm as someone with larger testicles.
Sometimes, testicles descend later in life, like during puberty. If a person's testicles never descend when they are young, they are more likely to develop cancer and infertility. A person with undescended testicles is unlikely to produce sperm, even with surgical correction.
Injury or trauma to the testicles, such as testicular torsion, can impair fertility. Additionally, heating the scrotum and testicles can create a sub-optimal environment for sperm production, resulting in lower sperm count and quality.