Vas deferens
The vas deferens, also known as the ductus deferens, is a crucial component of the male reproductive system. It is a smooth, muscular tube approximately eighteen inches long that transports sperm from the epididymis—where sperm is stored—to the urethra, facilitating ejaculation during sexual intercourse. Each male has two vasa deferentia, which begin at the epididymis, travel through the inguinal canal into the abdominal cavity, and curve behind the bladder. Here, they connect with the seminal vesicle, forming the ejaculatory duct that leads to the urethra.
Disorders related to the vas deferens can lead to infertility, including congenital defects or obstructions. A common medical procedure involving the vas deferens is a vasectomy, which is a form of male sterilization where the tubes are cut and sealed to prevent sperm from being part of the ejaculate. This outpatient procedure typically lasts about twenty minutes and requires follow-up testing to ensure the absence of sperm post-operation. While vasectomies can sometimes be reversed, potential complications include chronic pain and other physical changes in the area. Understanding the anatomy and function of the vas deferens can provide insight into male reproductive health and related medical interventions.
Subject Terms
Vas deferens
Also known as: Ductus deferens
Anatomy or system affected: Genitals, reproductive system
Definition: The tube that conveys sperm from the epididymis to the urethra in the male reproductive system
Structure and Functions
In the male reproductive system, the testes make sperm, which is then stored in an adjacent structure, the epididymis. The epididymis is connected to the urethra via the vas deferens (plural, vasa deferentia), a smooth tube about eighteen inches (forty-five centimeters) in length with thick, muscular walls that form part of the spermatic cord along with various nerves, muscles, and blood vessels.
A male has two vasa deferentia. From the epididymis, located to the rear of each testis, a vas deferens leads up into the abdominal cavity through the inguinal canal (a passageway through the abdominal wall). It curves around behind the bladder and, via an enlargement called the ampulla, merges with the seminal vesicle near the base of the bladder. From there, it passes through the prostate gland into the urethra.
During sexual intercourse, the walls of the vas deferens contract to move sperm out of the epididymis. The sperm mixes with seminal fluids from the seminal vesicle, prostate gland, and bulbourethral glands (Cowper’s glands). The ampulla and duct of the seminal vesicle together are the ejaculatory ducts through which sperm is propelled into the urethra for ejaculation from the penis.
Disorders and Diseases
Congenital defects of the male reproductive system that cause infertility include malformation or absence of one or both of the vasa deferentia. The exact mechanisms behind the defects are unknown, although there is a correlation with the genetic markers for cystic fibrosis. Obstructions in the vas deferens also occur, or an inguinal hernia may pinch it.
A principle means of contraception by sterilizing men involves the vas deferens. This is the vasectomy (also deferentectomy), in which the vasa deferentia are either cut and sealed, clipped, or injected with a material to block them. Urologists perform the procedure, usually during an office visit which takes about twenty minutes. It is necessary, three months following a vasectomy, for the patient to test their sperm count to ensure no sperm remain in the ejaculate. Possible complications include reduced sexual desire, bleeding, inflammation, sperm leakage, and spontaneous reopening. Postvasectomy pain syndrome is a condition of chronic pain in some men because of pressure, inflammation, or physical changes in the vas deferens. In some cases, a vasectomy can be reversed surgically so that the man is again fertile.
Bibliography
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“Vasectomy: Procedure, Recovery & Effectiveness.” Cleveland Clinic, 3 Feb. 2022, my.clevelandclinic.org/health/treatments/4423-vasectomy. Accessed 21 July 2023.