seminal vesicle


seminal vesicle
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]

* * *

      either of two elongated saclike glands that secrete their fluid contents into the ejaculatory ducts of some male mammals.

      The two seminal vesicles contribute approximately 60 percent of the fluids passed from the human male during ejaculation (q.v.). In some mammals the capacity of the seminal vesicles is much larger; the boar, for example, may emit up to 50 times as much seminal fluid. Carnivores, marsupials, monotremes, and cetaceans do not have seminal vesicles.

      The secretion of the seminal vesicles constitutes the bulk of the seminal fluid (semen). It is a thick fluid that contains the sugar fructose, proteins, citric acid, inorganic phosphorus, potassium, and prostaglandins (prostaglandin). Once this fluid joins the sperm in the ejaculatory duct, fructose acts as the main energy source for the sperm outside the body. Prostaglandins are believed to aid fertilization by causing the mucous lining of the cervix to be more receptive to sperm as well as by aiding the movement of the sperm toward the ovum with peristaltic contractions of the uterus and fallopian tubes.

      In the sexually mature human male, the seminal vesicles are elongated bodies 5 to 7 cm (2 to 2.75 inches) long and about 2 to 3 cm wide. In each vesicle is a tubule 15 cm long that is highly coiled and convoluted; surrounding this tube is connective tissue (blood and lymphatic vessels, nerve fibres, and supportive tissue). The tubule itself is composed of three layers: the inner lining, a moist and folded mucous membrane; a muscle layer of longitudinal and circular tissue; and a fibrous outside covering of elastic tissue. The mucous membrane secretes the fluids contributed by the seminal vesicles; it is highly folded while the tube is empty and can be distended without injury when its secretions cause it to fill the tubule. During ejaculation, the muscular tissue and elastic fibres contract to empty the vesicle's contents into the ejaculatory ducts shortly after the vas deferens has emptied the sperm into those ducts.

      The size and activity of the seminal vesicles are controlled by hormones. Production of androgen, the major hormone that influences the growth and activity of the seminal vesicles, begins at puberty and starts to decline at about the age of 30. In the absence of this hormone, the seminal vesicles will degenerate (atrophy).

* * *


Universalium. 2010.

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 — 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 …   Wikipedia

  • 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 — 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

  • seminal vesicle — noun /ˈsɛmɪnəlˌvɛsɪkl/ One of two simple tubular glands located behind the male urinary bladder, responsible for the production of about sixty percent of the fluid that ultimately becomes semen …   Wiktionary

  • seminal vesicle — Organ which stores sperm of male [Holdich and Jones, 1983]. Sac in male independent of testes for storage of spermatozoa (e.g., some anostracans, Chirocephalidae). (Syn. vesicula seminalis) [Moore and McCormick, 1969]. Sac in male, independent of …   Crustacea glossary

  • seminal vesicle — sem′inal ves′icle n. anat. either of two small saclike glands, located on each side of the bladder in males, that add nutrient fluid to semen during ejaculation • Etymology: 1885–90 …   From formal English to slang


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.