The vas deferens is a 45-55 cm long (2 mm in diameter) muscular tube; it has a very narrow lumen (0.2 mm). In living males it can be easily recognized by palpating a cartilage-hard structure within the scrotum, since the 90% of the thickness of its wall contains a compact, three-layered smooth muscle (which propels the sperm with its strong contractions from the epididymis into the urethra during ejaculation).
The ductus deferens starts from the tail of the epididymis – at the beginning it is very twisty, but shortly after it moves upwards behind the testis and epididymis, connected loosely to the mesorchium (epididymic / testicular part), then becomes a member of the spermatic cord, situated in it posteriorly (funicular part). First the spermatic cord courses freely (pars libera, free part), then enters the inguinal canal (inguinal part).
After leaving the deep inguinal ring, the vas deferens turns medially, crosses the inf. epigastric artery (coursing behind the artery) and crosses the external iliac artery and vein from superior, goes downwards. Causing a fold on the pelvic peritoneum, proceeds to medial direction (pelvic part), then crosses also the ureter (situated anteriorly from the ureter). The vas deferens here passes next to the fundus of the urinary bladder (vesical part), then it has a tortuous, dilated portion (ampullary part = ampulla of ductus deferens), after which the vas deferens gets again thinner and meets the excretory duct (of the seminal vesicle), forming an acute angle, and the two ducts unite to form the ejaculatory duct which finally opens into the prostatic part of the urethra.
During vasectomy the ductus deferens is ligated near the testis; this procedure prevents the transport of sperm. This surgical operation can be, in ideal cases a reversible male contraceptive method since this surgery leaves the male sex characteristics and the potentia coeundi unaffected.
III./1.3.2.:Blood supply
The blood supply comes from the internal iliac artery (a. of ductus deferens, deferential artery); this artery can also be seen in the spermatic cord.
Arteries can also arise from the superior vesical artery; in the scrotum anastomoses can be detected with the testicular artery, therefore the neighboring organs (testis, epididymis and ductus deferens) can receive arterial blood from several directions.
III./1.3.3.: Innervation
There is an especially important, rich plexus of sympathetic nerves (serving the smooth muscle contractions at ejaculation). The sympathetic nerves reach the ductus deferens from the hypogastric plexus. The parasympathetic nerves from the pelvic plexus are responsible for the continuous transmission of sperm cells via peristaltic movement of the vas deferens.
Utolsó módosítás: 2014. February 12., Wednesday, 10:28
