The seminal vesicles (glandulae vesiculosae) are a pair of simple tubular glands posteroinferior to the urinary bladder of males.
Anatomy
Each seminal gland spreads approximately 5 cm, though the full length of seminal vesicle is approximately 10 cm, but it is curled up inside of the gland's structure. Each gland forms as an outpocketing of the wall of ampulla of each vas deferens.
The excretory duct of seminal gland opens into the vas deferens as it enters the prostate gland.
Function
They secrete a significant proportion of the fluid that ultimately becomes semen. About 60% of the seminal fluid in humans originates from the seminal vesicles.
The thick secretions contain proteins, enzymes, fructose, mucus, vitamin C, flavins, phosphorylcholine and prostaglandins. The high fructose concentrations provide nutrient energy for the spermatozoa as they travel through the female reproductive system. The fluid is expelled under sympathetic contraction of the muscularis muscle coat.
Histology
Histologically, the seminal vesicles are notable for their tortuous pathways, diverticula, pseudo-stratified columnar epithelium and cuboidal cells along the basal layer.
The height of these columnar cells, and therefore activity, is dependent upon testosterone levels in the blood.
The lumen is large and stores the fluid secretions (but not spermatozoa) between ejaculations.
From inside to out, the layers are:
- Mucosa - arranged into convoluted folds, significantly increasing surface area
- Muscular - well-developed layer composed of an inner circular and outer longitudinal layer of smooth muscle
- Connective tissue
Additional images
Male reproductive system.
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Coronal section of pelvis, showing arrangement of fasciæ. Viewed from behind.
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Male pelvic organs seen from right side.
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Fundus of the bladder with the vesiculæ seminales.
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Vesiculæ seminales and ampullæ of ductus deferentes, seen from the front.
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Vertical section of bladder, penis, and urethra.
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Cross section of seminal vesicle through a microscope.
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External links
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