What is the seminal vesicle?
The seminal vesicle (vesicula seminalis) is a paired gland next to the prostate. It produces an alkaline and highly fructose-containing secretion that is added to the ejaculate. The proportion that this secretion contributes to the ejaculate varies between 60 and 70 percent.
How does the secretion get into the ejaculate?
From each of the two epididymis, a spermatic duct (Ductus deferens) runs from the scrotum through the inguinal canal into the pelvis. The right and left vas deferens unite with the excretory ducts of the two seminal vesicles, pass through the prostate and then flow into the urethra just below the bladder. In the further course, this is referred to as the urethral spermatic tube.
The sperm that come from the testicles or epididymis are thus mixed with the secretion of the seminal vesicles at the confluence of the vesicles’ excretory ducts. The prostate also contributes a secretion. The entire ejaculate is then transported to the outside via the urethral seminal vesicle during ejaculation.
What is the function of the seminal vesicle?
The paired seminal vesicle contributes a secretion to the ejaculate that supplies fructose (fruit sugar) to the sperm that come from the testes and epididymis. The sperm use the fructose as an energy source to be able to move.
The secretion of the seminal vesicle contains other substances as well: proteins such as semenogelin form a gel coat around the sperm in order to prevent their premature maturation (capacitation), which should only take place in the vagina through the secretion of the uterus (cervical secretion).
The secretion also contains prostaglandins – tissue hormones that promote contractions of the muscles of the female genital tract.
Where is the seminal vesicle located?
The seminal vesicles are located between the back of the urinary bladder and the wall of the rectum above the prostate. Their surface has a humped structure, and inside them are many mucosal folds of various sizes that form chambers. Sporadically, it may contain sperm, but in principle the paired seminal vesicle is not a reservoir for sperm, but a gland.
What problems can the seminal vesicle cause?
If the prostate is inflamed (prostatitis), the paired seminal vesicle may also be inflamed. Isolated inflammation of the seminal vesicle is rare.
Very rarely, tumors of the seminal vesicle occur (leiomyomas, carcinomas, and sarcomas). More common is tumorous infiltration (i.e., immigration of cancer cells) originating from prostate carcinoma (prostate cancer).
