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Seminal vesicle
Last reviewed: 23.04.2024
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The seminal vesicula (vesicula, s.glandula seminalis) is a paired organ located in the pelvic cavity lateral from the ampulla of the vas deferens, from the top of the prostate, from behind and from the side of the bottom of the bladder. The seminal vesicle is the secretory organ. Its glandular epithelium secretes a secret containing substances necessary for nutrition and activation of spermatozoa.
The peritoneum covers only the upper parts of it. The surface of the seminal vesicle is tuberous. The seminal vesicle has an anterior surface facing the bladder, and a posterior surface adjacent to the rectum. The length of the seminal vesicle is about 5 cm, the width is 2 cm, and the thickness is 1 cm. On the cut it has the appearance of blisters that communicate with each other. If the seminal vesicle partially remove the outer shell and spread it, it takes the form of a tubule 10-12 cm long and 0.6-0.7 cm thick.
Outside, the seminal vesicle has an adventitial tunic (tunica adventitia). Inside is a well developed muscularis (tunica muscularis), represented by two layers of smooth myocytes. The bundles of the inner layer have a circular orientation, the outer ones have a longitudinal orientation.
The mucosa (tunica mucosa) forms longitudinal folds, substantially increasing the surface of the secretory epithelium of the seminal vesicle. The epithelial cover is formed by high, cylindrical-shaped secretory cells on a thin basal membrane. Each seminal vesicle distinguishes the upper enlarged end - the base, the middle part - the body and the lower, tapering end, which passes into the excretory duct (ductus excretorius). The excretory duct of the seminal vesicle connects to the terminal section of the vas deferens and forms a ductus ejaculatorius, which perforates the prostate and opens into the prostate of the male urethra, to the side of the seminal mound. The length of the ejaculatory duct is about 2 cm, the width of the lumen is from 1 mm in the initial part to 0.3 mm at the point of confluence into the urethra.
The mucous membrane of the ejaculatory duct forms longitudinal folds, it is covered with a prismatic epithelium containing pigment granules. At the site of the passage of the duct through the prostate gland, its muscular membrane passes into the muscles of this gland.
Vessels and nerves of the seminal vesicle and vas deferens. The seminal vesicle is supplied from the descending branch of the artery of the vas deferens (branch of the umbilical artery). The ascending branch of the artery of the vas deferens brings blood to the walls of the vas deferens. The ampulla of the vas deferens receives blood through the branches of the middle rectal artery and the lower pancreatic artery (from the internal iliac artery).
Venous blood from the seminal vesicles through the veins flow into the venous plexus of the bladder, and then into the internal iliac vein. The lymph from the seminal vesicles and the vas deferens flows into the internal iliac lymph nodes. Seminal vesicles and the vas deferens receive sympathetic and parasympathetic innervation from the plexus of the vas deferens (from the lower hypogastric plexus).
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