Seminal vesicle

Seminal vesicle

Infobox Anatomy
Name = Seminal vesicle
Latin = vesiculæ seminales
GraySubject = 260
GrayPage = 1246


Caption = Male Anatomy


Caption2 = Prostate with seminal vesicles and seminal ducts, viewed from in front and above.
Width = 300
Precursor =
System =
Artery = Inferior vesical artery, middle rectal artery
Vein =
Nerve =
Lymph = external iliac lymph nodes, internal iliac lymph nodes
Precursor = Wolffian duct
MeshName = Seminal+Vesicles
MeshNumber = A05.360.444.713
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

The seminal vesicles secrete a significant proportion of the fluid that ultimately becomes semen. About 60% of the seminal fluid in humans originates from the seminal vesicles, but is not expelled in the first ejaculate fractions which are dominated by spermatozoa and zinc rich prostatic fluid. In vitro studies have shown that sperm expelled together with seminal vesicular fluid show poor motility and survival, and the sperm chromatin is less protected. Therefore the exact physiological importance of seminal vesicular fluid is not clear. It has been speculated that it is a developmental rest, still seen among some rodents where the last part of the ejaculate form a spermicidal plug which reduces the chances for sperm from a later arriving male to proceed to the oocyte.

The thick secretions contain proteins, enzymes, fructose, mucus, vitamin C, flavins, phosphorylcholine and prostaglandins. The high fructose concentrations provide nutrient energy for the spermatozoa when stored in semen in the laboratory. Spermatozoa ejaculated in the vagina are not likely to have contact with the seminal vesicular fluid but transfer directly from the prostatic fluid into the cervical mucus as the first step on their 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

External links

* - "Male Reproductive System: prostate, seminal vesicle"
* - "The Male Pelvis: The Urinary Bladder"
* - "The Male Pelvis: Structures Located Posterior to the Urinary Bladder"


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Look at other dictionaries:

  • seminal vesicle — n either of a pair of glandular pouches that lie one on either side of the male reproductive tract and that in human males secrete a sugar and protein containing fluid into the ejaculatory duct * * * either of a pair of male accessory sex glands… …   Medical dictionary

  • seminal vesicle cyst — a cyst in the wall of a seminal vesicle; it may be congenital and associated with other urinary tract anomalies, or acquired such as secondary to obstruction of the vesicle …   Medical dictionary

  • seminal vesicle calculus — a rare type of calculus found in a seminal vesicle, usually resulting from obstruction or infection. Called also gonecystic c …   Medical dictionary

  • seminal vesicle — Anat. either of two small saclike glands, located on each side of the bladder in males, that add nutrient fluid to semen during ejaculation. [1885 90] * * * ▪ anatomy       either of two elongated saclike glands that secrete their fluid contents… …   Universalium

  • seminal vesicle — the enlarged lower end of the genital duct which is secretory in nature and completes the formation of the spermatophores and stores them. The so called seminal vesicles of teleosts (Blennioidea, Gobioidea) are misnamed and do not store sperm;… …   Dictionary of ichthyology

  • seminal vesicle — n. seminal gland, one of the paired glands that produces seminal liquied …   English contemporary dictionary

  • seminal vesicle — 1. A male sac , tube or pouch like structure in which spermatozoa is stored before being discharged; seminal reservoir; vesicula seminalis. 2. (ANNELIDA) A pouch usually formed in a posterior septum of a testicular segment where the latter stages …   Dictionary of invertebrate zoology

  • seminal vesicle — either of a pair of male accessory sex glands that open into the vas deferens before it joins the urethra. The seminal vesicles secrete most of the liquid component of semen …   The new mediacal dictionary

  • seminal vesicle biopsy — The removal of fluid or tissue with a needle from the seminal vesicles for examination under a microscope. The seminal vesicles are glands in the male reproductive tract that produce a part of semen …   English dictionary of cancer terms

  • seminal vesicle — noun Date: circa 1890 either of a pair of glandular pouches that lie one on either side of the male reproductive tract and in the human male secrete a sugar and protein containing fluid into the ejaculatory duct …   New Collegiate Dictionary

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