Vas Deferens Function, Structure, Location and Pathway

Vas Deferens Function: The ductus deferens (or Vas Deferens) is a thick-walled tube in the male reproductive system that transports sperm from the epididymis to the urethra. Each tube ends in an ampulla, a reservoir for sperm. There are two identical ductus deferentes, one from each epididymis.

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Vas Deferens Definition

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Vas Deferens Functions

1. Sperm Transportation : The main function of the vas deferens is to carry sperm from the epididymis, where sperm are stored and matured, to the ejaculatory ducts during ejaculation. This transport allows sperm to move from the testes to the urethra, where they are expelled from the body during sexual intercourse.
2. Mixing with Seminal Fluid : As the vas deferens travels through the pelvic cavity, it collects secretions from the seminal vesicles, forming the ejaculatory duct. These secretions, combined with sperm from the vas deferens, create semen. Seminal fluid nourishes, protects, and aids in the mobility of sperm, improving their chances of fertilizing an egg.
3. Peristaltic Contractions : The smooth muscle surrounding the vas deferens contracts rhythmically during ejaculation, pushing sperm and seminal fluid through the ejaculatory ducts and out of the body. This rhythmic contraction helps ensure efficient semen expulsion.
4. Conduit for Semen : Together with the ejaculatory ducts, the vas deferens serve as a conduit for semen, transporting it from the reproductive organs to the urethra. Semen consists of sperm and fluids from the seminal vesicles, prostate gland, and bulbourethral glands. The vas deferens are essential for moving semen through the male reproductive tract.
5. Control of Sperm Release : Although not a direct function of the vas deferens itself, it is involved in the ejaculation process, which is controlled by the sympathetic nervous system. During sexual arousal, the brain signals the release of sperm from the epididymis into the vas deferens, ultimately leading to ejaculation.

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Structure of Vas Deferens

1. Epididymal Portion: This initial segment originates at the tail of the epididymis, a coiled tube where sperm are stored and matured.
2. Spermatic Cord Portion: As it leaves the epididymis, the vas deferens ascend through the inguinal canal within the spermatic cord, which also contains blood vessels, nerves, and lymphatics.
3. Pelvic Portion: Upon entering the pelvic cavity, the vas deferens travel along the posterior aspect of the bladder. It crosses the inguinal canal, curves around the inferior epigastric artery, and then moves anterior to the external iliac artery, crossing these vessels in a somewhat posterior and oblique direction.
4. Ampullary Portion : Near the base of the bladder, the vas deferens enlarges into the ampulla, a dilated section that receives secretions from the seminal vesicles.
5. Ejaculatory Duct Portion: The vas deferens then join with the duct of the seminal vesicle to form the ejaculatory duct. This portion passes through the prostate gland and empties into the urethra within the prostate.

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Course of the Vas Deferens

• Initially convoluted, the vas deferens straightens as it ascends posterior to the testis and medial to the epididymis.
• It travels superiorly along the posterior side of the spermatic cord, crossing the inguinal canal and emerging at the deep inguinal ring.
• It curves around the inferior epigastric artery and moves anteriorly to the external iliac artery.
• In the lesser pelvis, it traverses medially, positioned retroperitoneally and posterior to the obliterated umbilical artery, obturator vessels and nerves, and vesical vessels.
• It crosses the ureter at the posterolateral aspect of the bladder, forming the ampulla.
• Finally, it passes between the posterior bladder surface in an anteromedial direction, joining with the seminal vesicle duct to form the ejaculatory duct.

Location of Vas Deferens

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