The epididymis is an important reproductive organ of the male organism. In the epididymis, the sperm coming from the testes get their motility (mobility) and are stored until ejaculation.
What are the epididymis?
As an important part of the male sexual and reproductive organs, the two epididymis (epididymis) lie in the scrotum (scrotum) at the back on top of the paired testicles. The epididymis can be subdivided into a head, tail and tail section. They serve as storage and maturation sites for sperm, which pass through the approximately 5 m long, highly tortuous epididymal duct from the proximal segment (caput epididymidis or epididymal head) to the distal segment (cauda epididymidis or epididymal tail) within about 12 days, where they are stored until the next ejaculation. During their passage through the epididymal duct, sperm acquire, among other things, their motility (mobility), by which they are enabled to travel independently in the female genital tract.
Anatomy and structure
The epididymides, each about 5 cm in size, attach to the testes in the posterior upper region and taper downward in a crescent shape, where they open into a narrow canal. Generally, the epididymis are divided into a head, body and tail segment. About 12 to 15 excretory ducts of the testes (testes) open into the head of the epididymis (caput epididymidis) and, as single ducts, connect the ductus epididymidis (epididymal duct) of the epididymis to the rete testis of the testis. These then lead into the epididymid duct (ductus epididymidis), which is about 4 to 5 m long and runs through the entire epididymis and through which the sperm must pass. In the cauda epididymidis (epididymal tail), the ductus epididymidis merges into the ductus deferens (vas deferens). The epididymal ducts are lined by a bilayered cylindrical epithelium, on the surface of which there are a large number of stereovilli that provide surface enlargement and increased resorption and secretion. The epididymis is enveloped by the so-called tunica vaginalis testis (peritoneal sheath).
Functions and tasks
The epididymis plays an important role in reproduction as a storage and maturation site. Sperm that have not yet matured are directed to the epididymis for maturation via the ductuli efferentes (excretory ducts). When the sperm enter the epididymis, they are, among other things, not motile (capable of movement) and accordingly unable to fertilize an egg. During their passage through the epididymis or epididymal duct, as a result of contact with the epididymal wall, whose epithelial cells secrete glycoproteins that are adsorbed by the sperm, a tunnel protein (protein) is activated in the tail of the sperm that ensures calcium ion uptake, which provides the characteristic contractive swimming motion of the sperm. Before the spermatozoa can acquire this motility and move independently, the immature germ cells are transported peristaltically, i.e. by the contractile activity of the connective tissue (myofibroblasts), through the head and body section. The slightly acidic environment in the epididymal duct thereby inhibits sperm motility (acid torpor). However, the sperm only become capable of fertilization in the genital tract of the woman through the so-called capacitation (activation process). In the tail of the epididymis, the mature sperm are stored and collected until they are released from the epididymis into the vas deferens during ejaculation.
Diseases
The most common disease of the epididymis is acute or chronic inflammation, called epididymitis, which can be attributed to a variety of causes. For example, the epididymis may become inflamed as a result of a sexually transmitted infectious disease (including chlamydia, gonorrhea) that has spread to the epididymis. Epididymitis can also be caused by spread of bacterial prostatitis or bladder infections (including Escherichia coli, Proteus mirabilis, Enterococcus, Klebseria, Pseudomonas aeruginosa) through the spermatic cord, as well as by vasectomy or prostate resection. Inflammation of the epididymis is usually manifested by swelling and marked pain in the scrotum and epididymis.If left untreated, epididymitis can lead to abscess formation and/or degeneration of the fine epididymal ducts and ultimately the testis, resulting in infertility. In rare cases, benign tumors of the epididymis (cystadenomas) can be found in the context of Hippel-Landau disease, an autosomal-dominant inherited tumor disease, which can lead to infertility if they occur on both sides. The most common tumor of the epididymis is the mostly cherry-sized adenomatoid tumor (also mesothelioma), which is also benign. In addition, in about 20 to 30 percent, mumps disease (goatpeter) can be associated with orchitis (inflammation of the testicles), which in very rare cases can also affect the epididymis. In addition, cystic structures (spermatocele) may manifest in the epididymis, which are treated surgically only if they are associated with pain and family planning has been completed.
Typical and common testicular disorders
- Epididymitis
- Testicular cancer
- Undescended testis (maldescensus testis)
- Testicular pain
