Corpus: Spermatic duct

The ductus deferens is a part of the male genital tract. It is a tortuous muscular duct, approx. 50 cm long when unfolded, with a small star-shaped lumen and a thick three-layered musculature. Sperm are channelled from the epididymal duct into the ejaculatory duct by peristaltic movements.

Course[Bearbeiten]

The ductus deferens begins as a continuation of the ductus epididymidis at the epididymis and runs in the spermatic cord (funiculus spermaticus) through the inguinal canal into the pelvic cavity. It reaches the urinary bladder from the dorsal side. In this area it widens into the ampulla ductus deferentis and finally joins with the ductus excretorius of the vesicle gland to form the ejaculatory duct. The ejaculatory duct in turn opens into the urethra in the seminal vesicle (colliculus seminalis).

In its course, the ductus deferens crosses the following structures:

• Vasa epigastrica inferiora
• Vasa iliaca externa
• ureter

Supply[Bearbeiten]

The three-layered muscle layer of the ductus deferens is innervated sympathetically via the inferior hypogastric plexus during ejaculation. The arterial supply is via the ductus deferentis artery from the non-obliterated part of the umbilical artery ("pars patens"). The venous blood flows via the pampiniform plexus into the testicular veins and via the vesicoprostatic venous plexus and the vesical veins into the internal iliac vein.

The lymph of the vas deferens is drained via the nodi lymphatici iliaci interni and also partially via the nodi lymphatici lumbales.

The ductus deferens has a three-layered structure:

• The tunica mucosa consists of a two-row highly prismatic epithelium (cylindrical epithelium) with stereocilia, which has numerous longitudinal folds. The lamina propria mucosae is only weakly developed and contains elastic fibres that are connected to the tunica muscularis.
• In histological section, the tunica muscularis shows a three-layer structure consisting of an inner and outer longitudinal and a middle ring musculature. It is based on a spiral arrangement of the muscle cells, which serves the rapid transport of the sperm.
• The tunica adventitia contains connective tissue, blood vessels and nerves.

Surgical severing of both vas deferens leads to infertility. This procedure is performed for sterilisation and is called a vasectomy.

A congenital absence of one or both vas deferens is called vas deferens aplasia. It is associated with mutations in the CFTR gene and leads to infertility if it occurs bilaterally.

• Waldeyer et al, Human Anatomy: Textbook and Atlas in One Volume (De Gruyter Studium) (19th totaly rev. ed.), De Gruyter, 2012

• Course script Histology: A guide to microscopic anatomy, Faßbender, Ralf (author); 09/2020 Elsevier Verlag; used with the kind permission of the author