Sædlederne

Sædlederne, known in English as the vas deferentes, are a pair of muscular ducts that form part of the male reproductive system. They transport sperm from the epididymis to the ejaculatory ducts during ejaculation.

Anatomy: Each sædleder begins at the tail of the epididymis, ascends within the spermatic cord, traverses the inguinal canal, and enters the pelvic cavity. They run posterior to the bladder and terminate by joining the duct from the seminal vesicle to form the ejaculatory duct, which empties into the prostatic urethra. In adults they are roughly 40 cm long. The wall consists of mucosa, a submucosa, and a thick muscular coat that produces peristaltic contractions to propel sperm. They are supplied by branches of the testicular and inferior vesical arteries and are innervated by autonomic nerves.

Function: The sædlederne act as conduits that transport sperm from the epididymis toward the urethra. While they contribute little fluid themselves, smooth muscle contractions help move sperm during ejaculation.

Embryology: They develop from the Wolffian (mesonephric) ducts under the influence of androgens, forming part of the male internal genital tract.

Clinical significance: The ducts are a common target in sterilization procedures (vasectomy), which involves cutting or sealing the ducts to prevent sperm from entering semen. Obstruction, congenital absence (as seen in some cases of cystic fibrosis), or injury can cause male infertility and may require medical evaluation or assisted reproductive techniques.