Introduction
The epididymis is used for sperm cell maturation and storage of mature sperm cells. It is also part of the executive spermatic ducts. It is divided into three parts and lies on the testicle.
The development of the epididymis is directly associated with the development of the testes and kidneys. It develops in the embryonic period from the Wolff duct, after the genetic determination of the sex has taken place. The epididymis is the site of sperm cell maturation and serves as a storage for mature sperm cells.
In addition, the epididymis is also part of the executive spermatic ducts, since sperm are transported from the testes via parts of the epididymis and the epididymal duct. The epididymis lies above the testis and is slightly shifted backwards (craniodorsal). It is connected to the testis by an upper and a lower ligament (ligamentum epididymis superior and inferior).
The testis and epididymis are covered by various muscle fasciae. Between the two structures there is a small gap called the epididymal sinus. The epididymis is formed by many small executive ducts (Ductuli efferentes) and the epididymal duct (Ductus epididymidis).
These are very strongly constricted, in the extended state the epididymal duct is approx. 5m long, a small ductus efferens approx. 20cm long.
The epididymis is divided into three parts: By contractions of the muscles of the epididymis duct the spermatozoa are then released into the adjacent sperm duct (Ductus deferens). The diameter and lumen of the epididymal duct decrease towards the bottom (caudally). The mucosa of the epididymal duct consists of a double-row epithelium and branched sertoli cells.
In addition, the wall contains smaller myofibroblasts, which serve to contract the duct. The smaller Ductuli efferentes microscopically show an irregular undulating lumen. These are also surrounded by a sheath of contractile myofibroblasts.
- The head of the epididymis (Caput epididymidis) lies on top of the testis and contains 10-20 small ducts (Ductuli efferentes) and the beginning of the epididymal duct.
- The body of the epididymis (Corpus epididymidis) lies on the testis mainly from behind (dorsal). In this part the sperm cell storage takes place.
- The epididymis tail (Cauda epididymidis) is also the place where sperm cells are stored.
The arterial supply to the epididymis is through the arteria testicularis, the venous blood flow is through the pampiniform plexus. This is a venous plexus formed by the small testicular veins.
From there the blood continues to flow through the testicular veins (V. testicularis dexter and sinister) into the inferior vena cava. As in the testis, nerve innervation takes place via the coeliac plexus, whose fibers run together with the arterial vessels. These fibers form a nerve plexus near the kidney and from there they reach the testes and epididymis.
The parasympathetic fibers move as vegetative fibers to the epididymis. There, all nerve fibers together form the plexus testicularis and innervate the testes and epididymis. In epididymitis, an inflammatory process within the epididymis occurs due to various possible causes.
Preferably this disease occurs in men over 30 years of age and in children it is the cause of a so-called “acute scrotum” in only about 2% of cases. In adults, the cause of the disease is usually ascending germs from the prostate or the urethra, which enter the urethra mainly through urinary tract infections or during sexual intercourse. In addition to ascending causes, the inflammation can also occur via the blood, lymph, epididymal tubules, post-traumatic, immunological or viral (especially mumps).
In children, anomalies of the urogenital system, such as urethral valves, miscarriage or a “neurogenic bladder” are usually the cause of the disease. An epididymitis is an acute event, which usually worsens significantly within a single day and thus becomes symptomatic. The main symptom is increasing pain in the scrotum, which can radiate into the groin, abdomen and flank.
In most cases this also leads to redness and swelling of the scrotum (scrotum). Frequently a so-called positive “Prehn’s sign” can be detected. This means that the pain decreases when the affected testicle is lifted.
Often fever and fatigue are also possible. In the case of acute pain in the scrotal region, a urologist should be consulted quickly in any case in order to rule out a “testicular torsion“.Epididymitis is mainly treated by elevating the epididymis, cooling, strict bed rest and application of an ointment. In addition, antibiotics can be administered and/or local painkillers injected.
Since the epididymis lies directly on the testis and is connected to it, it is important to distinguish whether pain or swelling affects the testis, the epididymis or both. This can often be difficult to assess and should be clarified by a doctor. The most common reason for swelling in the area of the epididymis is the epididymitis already described above.
This can also occur in conjunction with an inflammation of the testes and is then called “epididymal moorchitis”. Other possible causes besides an inflammation are cysts (spermatocele), abscesses, varicose vein rupture (varicocele), hydrocele, thrombosis, tumors, hernias, a testicular torsion or sperm granulomas. A sperm granuloma is a change in hard, nodular form in the spermatic cord, which is caused by sperm leaking into the surrounding tissue.
There are several criteria for distinguishing between these different causes. If pain occurs in addition to swelling, it is most likely to be an inflammatory process, an abscess, a thrombosis, a tumor or gangrene (tissue necrosis). In addition, further differentiation is possible by precise palpation of the swelling.
It is particularly important to know where the swelling is located, how far it extends, whether it covers the entire testicle or only a part of it and what consistency the swelling has. However, only a urologist is able to make a precise diagnosis and should be consulted for any changes that are detected. An epididymal cyst, also known as a spermatocele or “retention cyst”, is caused by an obstruction in the flow of fluid within the epididymis.
Since the epididymis serves the transmission and maturation of sperm at the transition from the testicles to the vas deferens, an accumulation of protein-containing sperm occurs. This obstruction is usually caused by different or unusual epididymal tubules, but can also be caused by surgery or by a past epididymitis. Such obstruction and congestion of sperm is very common and can be found in about 80% of men.
However, since it is very small in the majority of cases, it usually does not cause any problems and is therefore only discovered by chance at most. A small percentage (5%), however, results in a strong increase in size, in which the cyst can reach diameters of more than 10cm. As the size increases, there are also symptoms such as pain and a feeling of pressure in the epididymis.
If an epididymal cyst is discovered by chance and manifests itself without symptoms, no further therapy is necessary. However, if a spermatocele is noticed due to pain or a feeling of pressure, surgical removal is indicated. Epididymal pain is a very common symptom, which can often be acute but can also be chronic.
As in the case of swelling of the epididymis, it is sometimes difficult to differentiate between the testicles and the epididymis, which is why a disease of the respective other organ can also be a cause. The most frequent cause of a painful epididymis in adults is the above-mentioned epididymitis. In children, the most common cause of a painful, acute scrotum is a testicular torsion (testicular torsion), which is an emergency and must be treated as soon as possible.
Other possible causes are abscesses, tumors, thromboses, external injuries or tissue necrosis. A reasonably good way to distinguish between inflammation and testicular torsion is the so-called “Prehn’s test”. In the case of inflammatory processes, pain is usually relieved when the affected testicle is lifted (positive Prehn’s sign).
In addition to pain in the epididymis, there are often other accompanying symptoms such as swelling, redness, rash, feeling of pressure or heaviness, as well as fever and weakness. Particularly in the case of rapidly increasing and/or suddenly occurring pain, a urologist should be consulted as soon as possible to rule out a urological emergency or to treat it in time. Surgical removal may be necessary in case of chronic and recurrent epididymitis or hydrocele.
Other reasons for surgical resection are tumors, recurrent inflammation and other rather rare causes, which are individually assessed by the respective urologist.In epididymectomy, a part of the spermatic duct is often also removed to reduce the likelihood of postoperative complications (epididymovasectomy). During surgery, the epididymis is removed through a small incision in the scrotum. Since usually only one side is affected by the inflammation or hydrocephalus rupture, compensation is provided by the healthy side, so fertility and erection are not restricted.
However, postoperative complications, such as wound healing disorders or infections, are common during this procedure. There is also the risk of a “descending” inflammation, which can lead to the need for additional removal of the testicle afterwards. Epididymal cancer is a very rare disease compared to testicular cancer (about 10 times more frequent).
There is a nodular change/swelling within the scrotum, which is usually noticed by the patients themselves. Epididymal tumors are rather slow growing, mostly painless tumors, which is why they can go unnoticed for a long time. In order to confirm the suspicion, an ultrasound is first made.
If a mass is detected, the testis and epididymis are exposed and a microscopic tissue examination is performed to make an exact diagnosis and differentiate between benign and malignant tumors. A palpable nodular change in the epididymis can have many causes. In most cases it is a cyst, an abscess or an inflammation.
In rare cases it can also be a tumor or a thrombosis. An important distinguishing feature is the existing pain, which rather points to inflammatory or thrombotic processes. However, a bulging, painless swelling is most likely to indicate a cyst (spermatocele).
In any case, a urologist should be consulted. The epididymis is part of the epididymal ducts and is used for the maturation and storage of sperm cells. It lies on top of the testis and is bordered by various muscle fasciae together with the testis.
It is connected to the testes by two ligaments. The epididymis consists of numerous small ducts (Ductuli efferentes) and a larger excretory duct (Ductus epididymis). It serves the maturation and storage of sperm cells and transmits them to the seminal duct by contraction of the epididymal duct. The vascular supply and nerve innervation is carried out together with the testis.