The vas deferens, also referred to as the ductus deferens, is a muscular tube like structure found in the spermatic cord forming the main component of the male reproductive system. This forms the continuation of the epididymis participating in the transportation of the spermatozoa from the epididymis to the ejaculatory ducts.
The vas deferens is a 45 cm long structure found posterior to the testis and medial to the epididymis in the spermatic cord. It unites with the duct of the seminal vesicle to form the ejaculatory duct.
At the start it is convoluted, gets straight as it ascends in its course posterior to the testis and medial to the epididymis. On reaching the peak of testis, it superiorly travels to the posterior of the spermatic cord. It then crosses the inguinal canal before they emerge from the spermatic cord at the deep inguinal ring. Post this, it curves around the inferior epigastric artery projecting anterior to the external iliac artery. It then crosses these iliac vessels in a somewhat posterior and oblique direction.
Upon entering the lesser pelvis after that, it medially traverses where it is retroperitoneal and posterior to the obliterated umbilical artery, obturator vessels and nerves and vesical vessels. The vas deferens then crosses to the ureter at the posterolateral direction of the bladder, post which it expands and is known as the ampulla. Following this, it passes between the posterior surface of the bladder in an anteromedial direction and upper aspect of the seminal vesicle.
The vas deferens is then passing along the base of the bladder inferiorly and then anteriorly to the rectum before joining the duct of the seminal vesicle at an angle forming the ejaculatory duct.
Function of Vas Deferens
The main function of vas deferens is in transporting the spermatozoa from the epididymis all the way to the ejaculatory ducts. The sympathetic nervous system during ejaculation innervates the muscular layers of the ductus deferens causing them to generate strong peristaltic contractions to assist in the propulsion of the spermatozoa. Consequently, the vas deferens transports nature sperms to the urethra hence helps to prepare for ejaculation.
The smooth muscles in the walls of the vas deferens during ejaculation reflexively contract causing sperms to move forward. This is peristalsis. Sperms are passed from vas deferens into the urethra mixing partially with the secretions from the male accessory glands such as the prostate glands, seminal vesicles and the bulbourethral glands.
The ductus deferens is rendered with an artery of vas deferens which emerges from the superior or inferior vesical artery.
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