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The seminal vesicles are a pair of simple tubular glands posteroinferior to the urinary bladder, and lateral to the vas deferens.
They secrete fluid that partly composes a significant amount of the semen.
Each seminal vesicle consists of a single tube folded and coiled on itself.
There are occasional diverticula in the wall of the seminal vesicle.
The seminal vesicle excretory duct unites with the vas deferens to form the ejaculatory ducts.
The ejaculatory ducts pass through the prostate gland before opening separately into the verumontanum of the prostatic urethra.
The seminal vesicle spans approximately 5 cm, but its full unfolded length is approximately 10 cm.
Each vesicle forms as an outpocketing of the wall of the ampulla of the vas deferens.
Its lumen is highly irregular and stores secretions from the glands of the vesicles
Its mucosa is pseudostratified columnar in character, and the height of these columnar cells is dependent upon testosterone levels in the blood.
Its lamina propria, contains small blood vessels and lymphatics, with the epithelium.
Spermatozoa may occasionally be found within the lumen of the glands, due to slight reflux due to muscular contractions of the urethra during ejaculation.
Its secretions have a yellowish color from lipofuscin granules from dead epithelial cells.
About 70-85%of the seminal fluid in humans originates from the seminal vesicles.
However, the first ejaculate fractions are dominated by spermatozoa and zinc-rich prostatic fluid.
The seminal gland excretory duct opens into the corresponding vas deferens as it enters the prostate gland.
Seminal vesicle fluid is mildly alkaline.
The alkalinity of semen helps neutralize vaginal tract acidity prolonging the lifespan of sperm.
An acidic ejaculate may be associated with ejaculatory duct obstruction.
Semenogelin, is produced in the seminal vesicles.
Semenogelin, is a protein that causes semen to become sticky and jelly-like after ejaculation.
Seminal vesicle secretions contain proteins, enzymes, fructose, mucus, vitamin C, flavins, phosphorylcholine and prostaglandins.
Androgens are involved in the development and maintenance of the seminal vesicles.
Androgens also involved in seminal vesicle secretion size, and weight,.
The seminal vesicles contain 5α-reductase.
5α-reductase metabolizes testosterone into the much more potent metabolite, dihydrotestosterone (DHT).
The seminal vesicles have also been found to contain luteinizing hormone receptors.
Seminal vesicle fluid analysis requires a semen sample.
Seminal vesicle fructose levels provide a measure of its function, and in its absence, suggests obstruction or agenesis.
The seminal vesicles are susceptible to: vesiculitis, acquired cysts, abscess formation,, congenital anomalies, amyloidosis, tuberculosis, schistosomiasis, hytatid cyst, stones, and tumors.
Rarely, adenocarcinoma of the seminal vesicles has been reported, and is the most common neoplasm of the seminal vesicles.
More rare neoplasms include sarcoma, squamous cell carcinoma, yolk sac tumor, neuroendocrine carcinoma, paraganglioma, epithelial stromal tumors and lymphoma.
Seminal vesical inflammation is most often caused by bacterial infection.
Seminal vesical inflammation can manifest as vague back or lower abdominal pain, penile, scrotal, or perineal pain, painful ejaculation; hematospermia, irritative and obstructive voiding symptoms, and impotence.
Seminal vesical inflammation is usually treated by administration of antibiotics.