Testicles – Anatomy, Function, and Importance of the Testis, and Information on the Scrotum

The testicles (testes) are a pair of male reproductive organs. They are the male counterpart to the female ovaries and are classified as gonads. The testicles produce sperm (semen) as well as hormones, the regulation of which is controlled by the pituitary gland and the hypothalamus. Furthermore, they are an indispensable component of sexual reproduction.

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An important function of the testes is the production of hormones (androgens) and sperm, which are essential for reproduction.

Hormone synthesis is carried out by the Leydig cells. They primarily produce testosterone. The hormone testosterone plays a significant role in stimulating sperm production. In addition, they contribute to the development and function of the other reproductive organs.

Sertoli cells are primarily responsible for sperm development and promote it. They form a supportive cellular framework in which the germ cells mature.

The epididymis serves as a sperm reservoir. It also supports the sperm as they mature.

During puberty, up to 200 million sperm are produced daily. Each sperm takes about two months to mature. Hormones are responsible for regulating this process. During ejaculation, the sperm mix with seminal fluid. This fluid is produced in the prostate and the seminal vesicles before ejaculation.

The testicles hang freely from the spermatic cord in the scrotum. They are elongated in shape and have a diameter of about three centimeters. They are approximately four centimeters long, and their weight ranges from 25 to 30 grams. At the upper end of both testicles is the head of the epididymis.

The size of the testicles varies from man to man. Starting in puberty, their size increases and reaches its maximum between the ages of 30 and 40. After age 50, the size of the testicles decreases slightly. 

Components of the Testicle

The testicle is enclosed by connective tissue (tunica albuginea). Internally, it is divided into more than 200 to 300 lobules. These are separated from one another by walls. Another component of the testis is the rete testis, which consists of several channels that branch out and are located within the testicular lobules. The Sertoli cells, which support the sperm precursors, are housed within the seminiferous tubules.

The cells located between the seminiferous tubules are called Leydig cells. Their function is to produce the male sex hormone testosterone.

The testis is supplied with blood by the testicular artery, which is a branch of the abdominal aorta. Venous blood is collected bilaterally in the pampiniform plexus, a network of veins.

The Epididymis

The epididymis is located on the posterior side of the testis. The epididymis is closely fused to the testis. It has a diameter of 5 to 10 millimeters and a length of 5 centimeters. It is surrounded by a thin capsule and sits like a cap over the testicle. It is connected to the urethra via the vas deferens, which is located within the prostate. In this way, the sperm produced in the testicle are transported out of the man’s body during ejaculation. The vas deferens is 30 to 40 centimeters long.

There are various testicular disorders that should be taken seriously because they can impair a man’s fertility. In some cases, they cause irreversible damage. Men between the ages of 20 and 40 are most commonly affected by these disorders.

Testicular torsion

One of the most common testicular conditions is testicular torsion, which involves a twisting of the testicle. This injury is usually caused by physical trauma, such as a kick to the testicles. In some people, however, testicular torsion is congenital. In the case of testicular torsion, the testicle and the epididymis become twisted around the testicular pedicle, which in turn results in an interruption of the blood supply.

Since testicular torsion is a medical emergency, immediate surgical treatment is required. 

Testicular inflammation (orchitis) is relatively common. It is caused by injuries to the scrotum that allow bacteria to enter the testicle. Infectious diseases are another possible cause.

In cases of orchitis, the testicle swells and becomes painful. It is not uncommon for the scrotum to become red. Treatment involves cooling the testicle and elevating it. The patient is also prescribed an appropriate antibiotic.

Another condition is epididymitis. In this case, one epididymis is usually affected by an infection.

Inflammation of the epididymis often first manifests as a burning sensation during urination. Later, redness, swelling, and severe pain in the genital region may develop. The condition may be accompanied by fever, chills, and general flu-like symptoms.

Epididymitis is usually treated with local anesthesia of the spermatic cord and a course of antibiotics lasting several weeks. If the infection does not clear up in time, there is a risk that the epididymis will need to be surgically removed.

In 15–20 percent of cases, the condition can also develop into a chronic form.

Undescended Testicles

Undescended testicles are a relatively common developmental abnormality. The testicles of male fetuses form in the abdominal cavity. From there, they usually descend into the scrotum before birth, though sometimes this occurs after birth.

Cryptorchidism is diagnosed when one or both testicles have not fully descended into the scrotum. A distinction is made between intra-abdominal testicles, inguinal testicles, sliding testicles, and pendulous testicles, although the latter are likely not associated with an increased risk of disease.

About 2 to 4 percent of all male newborns are born with undescended testicles. If the testicles have not fully descended into the scrotum by the age of one, surgical intervention is necessary. Undescended testicles lead to an increased risk of testicular cancer later in life.

Testicular cancer is one of the most common forms of cancer in young men. Risk factors such as undescended testicles contribute to this disease. The cancer usually presents as a painless lump.

Testicular cancer is considered highly treatable. Cure rates in the early stages range from 98 to 100 percent. Treatment involves the removal of one testicle (orchiectomy). Chemotherapy, radiation therapy, or watchful waiting are also options.

A hydrocele is the accumulation of serous fluid in the testicle. It can occur on one side or both sides and leads to a usually painless swelling of the scrotum. Possible causes include:

• Genetic predisposition
• Tumors
• Inflammation
• Injuries

If the hydrocele causes discomfort, it can be removed through surgery.

Varicocele

A varicocele, also known as a varicose vein of the testicle, develops due to the dilation of the testicular veins. It is characterized by twisted veins. Pain, however, is rare. It can sometimes lead to infertility. Treatment involves sclerotherapy or surgical removal.

One of the most important methods in urology for detecting testicular disorders is palpation of the organ. During this procedure, the doctor examines the position, size, and consistency of the testicle. Additionally, imaging techniques such as sonography (ultrasound) are used.

To determine testicular volume, an ultrasound measurement is performed or a comparison is made using the Prader scale. For some conditions, a testicular biopsy is also performed, during which a small sample of tissue is removed.

When the first symptoms appear, patients can consult their primary care physician. If further questions arise—for example, if suspicion of a disease affecting the genital region is confirmed—the primary care physician will typically refer the patient to a specialist.

Urologists specialize in the treatment of urinary tract and genital diseases. They diagnose conditions affecting the penis, testicles, prostate, or urinary tract, as well as associated organs such as the bladder.

Men aged 25 and older, in particular, should undergo a general urological examination every year to detect malignant diseases early, prevent risks, and potentially take initial preventive measures.

The two testicles are paired organs and are among the most important internal male reproductive organs; human testicles are highly specialized structures. The structure of the testis is evident in both macroscopic and microscopic anatomy, featuring structures such as the lobuli testis, seminiferous tubules, and contorted seminiferous tubules, which are organized within the mediastinum testis. They are surrounded by the tunica vaginalis testis, the periorchium, and the internal spermatic fascia, while the medial and lateral surfaces determine their external shape.

The testes are located in the scrotum, a skin sac between the legs, and can be palpated there as the testes within the scrotum as well as through the scrotum, with the right testis often lying slightly lower. It is important to note that the temperature in the scrotum is optimal, as temperature-sensitive sperm require these conditions, allowing for the production of millions of sperm daily—approximately 200 million sperm per day. Testicle size increases over the course of a man’s life and varies from man to man, with larger testicles often associated with greater reproductive function.

Functionally, the testicles and epididymis are closely linked, as sperm cells are stored in the epididymis, while hormone production in the testicles ensures the production of male sex hormones, and the testicles produce the male sex hormone testosterone, regulated by LH and FSH. Overall, it is evident that the testis consists of complex tissues and that its innervation and blood supply are essential for its function.

From a developmental perspective, the testicles develop within the abdominal cavity; during embryonic development, they form in the abdomen of the fetus and migrate through the inguinal canal into the scrotum, making their formation within the abdominal cavity a crucial step. Disorders such as cryptorchidism demonstrate how important this process is, as the testes may otherwise remain in the abdominal cavity.

In summary: The testes are vital organs responsible not only for reproduction but also for hormonal regulation, and their complex structure ensures these functions. Conditions such as testicular tumors can impair their function, which is why changes should be detected early.

What are the testicles, and what is their function?

The testicles are male reproductive organs that produce sperm and testosterone. They are essential for reproduction and the development of male characteristics.

Where are the testicles located in the body?

The testicles are located in the scrotum outside the abdominal cavity. This location is important because the temperature there is lower, which supports sperm production.

What is the epididymis?

The epididymis is a part of the male reproductive system where sperm cells mature and are stored. It lies directly on top of the testicle.

What conditions can affect the testicles?

The most common conditions include testicular cancer, inflammation, and developmental disorders such as undescended testicles (maldescensus testis).

How are sperm produced in the testicles?

Sperm are produced in the seminiferous tubules through spermatogenesis. Sertoli cells and Leydig cells play an important role in this process.