The ejaculatory ducts are a pair of tubular anatomical structures in the male reproductive system that move sperm from the vas deferens to the penis during ejaculation. These ducts are less than an inch in length and are formed by the convergence of two other systems of ducts in the male reproductive system, the vas deferens and the excretory ducts of the seminal vesicles. The ejaculatory ducts are located near the base of the prostate gland. Blockage or obstruction of the ejaculatory ducts can lead to conditions such as failure to produce semen, low levels of sperm in the semen, and male infertility.
Ejaculatory ducts are sometimes considered to be accessory glands of the male prostate. Their structure includes a thin outer layer that is coarse and fibrous, which is virtually nonexistent by the time the ducts enter the prostate. Inside the fibrous outer layer are layers of muscular tissue and a mucous membrane. The ducts narrow as they pass through the prostate gland and end in a pair of small, slit-like openings. These openings are connected to a small, elevated area called the seminal colliculus, which in turn connects to a fold of tissue at the rear wall of the urethra called the urethral crest.
Sperm is formed in the male testes and stored in the left and right epididymis. Before ejaculation can occur, sperm must travel into the ducts of the vas deferens. During ejaculation, wavelike involuntary muscle contractions push the sperm out of the vas deferens and into the ejaculatory ducts via a process called peristalsis. The ejaculatory ducts move sperm towards the urethra, collecting other components of semen from the seminal glands, the bulbourethral glands, and finally, the prostate. Semen is drained from the ejaculatory ducts into the seminal colliculus, then travels through the urethra, and leaves the body through the tip of the penis.
Ejaculatory duct obstruction (EDO) is a somewhat rare condition resulting in approximately 1 to 5 percent of male infertility. It is usually caused by a previous urinary tract infection or by surgical procedures conducted on the bladder, urethra, prostate, or related structures. Symptoms of EDO include infertility, an extremely low sperm count termed azoospermia, either a low volume of semen termed oligospermia or a total lack of semen termed aspermia, and pelvic pain, particularly following ejaculation. An invasive urological operation to reverse EDO, called transurethral resection of the prostate, is one of the only existing methods of treatment.