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The seminal vesicles (also called vesicular glands (2025). 9780813813943, John Wiley and Sons. ISBN 9780813813943 or seminal glands) are a pair of convoluted tubular accessory glands that lie behind the urinary bladder of male mammals. They secrete fluid that largely composes the semen.
The vesicles are 5–10 cm in size, 3–5 cm in diameter, and are located between the urinary bladder and the rectum. They have multiple outpouchings, which contain secretory glands, which join together with the vas deferens at the . They receive blood from the vesiculodeferential artery, and drain into the vesiculodeferential veins. The glands are lined with column-shaped and cuboidal cells. The vesicles are present in many groups of mammals, but not marsupials, monotremes or carnivores.
Inflammation of the seminal vesicles is called seminal vesiculitis and most often is due to bacterial infection as a result of a sexually transmitted infection or following a surgical procedure. Seminal vesiculitis can cause pain in the lower abdomen, scrotum, penis or peritoneum, painful ejaculation, and haematospermia. It is usually treated with antibiotics, although may require surgical drainage in complicated cases. Other conditions may affect the vesicles, including congenital abnormalities such as failure or incomplete formation, and, uncommonly, tumours.
The seminal vesicles have been described as early as the second century AD by Galen, although the vesicles only received their name much later, as they were initially described using the term from which the word prostate is derived.
The vesicles receive blood supply from the vesiculodeferential artery, and also from the inferior vesical artery. The vesiculodeferential artery arises from the umbilical arteries, which branch directly from the internal iliac arteries. Blood is drained into the vesiculodeferential veins and the inferior vesical plexus, which drain into the internal iliac veins. Lymphatic drainage occurs along the venous routes, draining into the internal iliac nodes.
The vesicles lie behind the bladder at the end of the vasa deferentia. They lie in the space between the bladder and the rectum; the bladder and prostate lie in front, the tip of the ureter as it enters the bladder above, and Denonvilliers' fascia and the rectum behind.
In the male, under the influence of testosterone, the mesonephric ducts proliferate, forming the epididymis, ductus deferens and, via a small outpouching near the developing prostate, the seminal vesicles. secrete anti-Müllerian hormone, which causes the paramesonephric ducts to regress.
The development and maintenance of the seminal vesicles, as well as their secretion and size/weight, are highly dependent on . The seminal vesicles contain 5α-reductase, which metabolizes testosterone into its much more potent metabolite, dihydrotestosterone (DHT). The seminal vesicles have also been found to contain luteinizing hormone receptors, and hence may also be regulated by the ligand of this receptor, luteinizing hormone.
About 70-85% of the seminal fluid in humans originates from the seminal vesicles. (2025). 9780323078429, Mosby. ISBN 9780323078429 The fluid consists of nutrients including fructose and citric acid, , and fibrinogen. Fructose is not produced anywhere else in the body except in the seminal vesicles. It provides a forensic test in rape cases.
Nutrients help support sperm until fertilisation occurs; prostaglandins may also assist by softening mucus of the cervix, and by causing reverse contractions of parts of the female reproductive tract such as the , to ensure that sperm are less likely to be expelled.
Congenital anomalies associated with the seminal vesicles include failure to develop, either completely (agenesis) or partially (hypoplasia), and . Failure of the vesicles to form is often associated with absent vas deferens, or an abnormal connection between the vas deferens and the ureter. The seminal vesicles may also be affected by , amyloidosis, and stones. Stones or cysts that become infected, or obstruct the vas deferens or seminal vesicles, may require surgical intervention.
Seminal vesiculitis (also known as spermatocystitis) is an inflammation of the seminal vesicles, most often caused by bacterial infection. Symptoms can include vague back or lower abdominal pain; pain of the penis, scrotum or peritoneum; painful ejaculation; Haematospermia on ejaculation; irritative and obstructive voiding symptoms; and impotence. (1999). 9781901865042, CRC Press. ISBN 9781901865042 Infection may be due to sexually transmitted infections, as a complication of a procedure such as prostate biopsy. It is usually treated with . If a person experiences ongoing discomfort, transurethral seminal vesiculoscopy may be considered. Intervention in the form of drainage through the skin or surgery may also be required if the infection becomes an abscess. The seminal vesicles may also be affected by tuberculosis, schistosomiasis and hydatid cyst. These diseases are investigated, diagnosed and treated according to the underlying disease.
Benign tumours of the seminal vesicles are rare. When they do occur, they are usually papillary adenomata and cystadenomata. They do not cause elevation of Tumor marker and are usually diagnosed based on examination of tissue that has been removed after surgery. Primary adenocarcinoma, although rare, constitutes the most common malignant tumour of the seminal vesicles; that said, malignant involvement of the vesicles is typically the result of local invasion from an extra-vesicular lesion. When adenocarcinoma occurs, it can cause blood in the urine, blood in the semen, painful urination, urinary retention, or even urinary obstruction. Adenocarcinomata are usually diagnosed after they are excised, based on tissue diagnosis. Some produce the tumour marker Ca-125, which can be used to monitor for reoccurence afterwards. Even rarer neoplasms include sarcoma, squamous cell carcinoma, yolk sac tumour, neuroendocrine carcinoma, paraganglioma, epithelial stromal tumours and lymphoma.
A digital rectal examination, which involves a finger inserted by a medical practitioner through the anus, may cause greater than usual tenderness of the prostate gland, or may reveal a large seminal vesicle. Palpation is dependent on the length of index finger as seminal vesicles are located above the prostate gland and retrovesical (behind the bladder).
A urine specimen may be collected, and is likely to demonstrate blood within the urine. Laboratory examination of seminal vesicle fluid requires a semen sample, e.g. for semen culture or semen analysis. Fructose levels provide a measure of seminal vesicle function and, if absent, agenesis or obstruction is suspected.
Imaging of the vesicles is provided by medical imaging; either by transrectal ultrasound, CT or MRI scans. An examination using cystoscopy, where a flexible tube is inserted in the urethra, may show disease of the vesicles because of changes in the normal appearance of the nearby bladder trigone, or prostatic urethra.
The first described use of laparoscopic surgery on the vesicles was described in 1993; this is now the preferred approach because of decreased pain, complications, and a shorter hospital stay.
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