Vas deferens

Source: Wikipedia, the free encyclopedia.
Vas deferens
artery of the ductus deferens
LymphExternal iliac lymph nodes, internal iliac lymph nodes
Identifiers
Latinvas deferens (plural: vasa deferentia),
ductus deferens (plural: ductus deferentes)
MeSHD014649
TA98A09.3.05.001
TA23621
FMA19234
Anatomical terminology]
3D Medical Illustration showing vas deferens.
3D medical illustration showing vas deferens.

The vas deferens (pl.: vasa deferentia), with the more modern name ductus deferens (pl.: ductūs deferentes), is part of the male

vertebrates. The ducts transport sperm from the epididymides to the ejaculatory ducts in anticipation of ejaculation. The vas deferens is a partially coiled tube which exits the abdominal cavity through the inguinal canal
.

Etymology

Vas deferens is Latin, meaning "carrying-away vessel" while ductus deferens, also Latin, means "carrying-away duct".[1]

Structure

The human vas deferens measures 30–35 cm in length, and 2–3 mm in diameter.

duct of the seminal vesicle to form the ejaculatory duct.[3] Together they form part of the spermatic cord.[4]

Blood supply

The vasa deferentia are supplied with blood by accompanying arteries, the (

internal iliac arteries.[5]

Innervation

The vas deferens receives innervation from an autonomic plexus of post-ganglionic sympathetic fibres derived from the inferior hypogastric plexus.[2]: 1297 

It is innervated by a variety of

noradrenaline) are found in the smooth muscle layers.[7] Cholinergic synapses and vasoactive intestinal peptide synapses are found in the connective tissue of the mucosa.[8]

Anatomical relations

Within the spermatic cord, the vas deferens is situated posterior (and parallel to) the vessels of the spermatic cord.[2]: 1297 

The vas deferens traverses the inguinal canal to reach the

inferior epigastric vessels. At the deep inguinal ring, the vas deferens diverges from the testicular vessels to pass medially to reach the base of the prostate posteriorly.[2]
: 1297 

Histology

The vas deferens consists of an external adventitial sheath containing blood vessels and nerves, a muscular middle layer composed of three layers of smooth muscle (with a circular muscle layer interposed between two longitudinal muscle layers), and an internal mucosal lining consisting of pseudostratified columnar epithelium (which bears the non-motile stereocilia).[2]: 1297 [9]

The vas deferens has the greatest muscle-to-lumen ratio of any hollow organ.[2]: 1297 

Function

During

prostate gland and the bulbourethral glands, which form the bulk of semen.[11]

Clinical significance

Contraception

A

contraception in which the vasa deferentia are permanently cut. In some cases, it can be reversed. A modern variation, vas-occlusive contraception, involves injecting an obstructive material into the ductus to block the flow of sperm.[12]

Disease

The vas deferens may be obstructed, or it may be completely absent in a condition known as congenital absence of the vas deferens (CAVD, a potential feature of cystic fibrosis), causing male infertility. Acquired obstructions can occur due to infections. To treat these causes of male infertility, sperm can be harvested by testicular sperm extraction (TESE) or microsurgical epididymal sperm aspiration (MESA).[13]

Uses in pharmacology and physiology

The vas deferens has a dense sympathetic innervation,[14] making it a useful system for studying sympathetic nerve function and for studying drugs that modify neurotransmission.[6]

It has been used:

  • as a bioassay for the discovery of enkephalins, the endogenous opiates.[15]
  • to demonstrate quantal transmission from sympathetic nerve terminals.[16]
  • as the first direct measure of free Ca2+ concentration in a postganglionic nerve terminal.[17]
  • to develop an optical method for monitoring packeted transmission (similar to quantal transmission).[18]

Other animals

Most vertebrates have some form of duct to transfer the sperm from the

placental mammals, but not in marsupial mammals.[20][21]

In cartilaginous fishes, the part of the archinephric duct closest to the testis is coiled up to form an epididymis. Below this are a number of small glands secreting components of the seminal fluid. The final portion of the duct also receives ducts from the kidneys in most species.[19]

In amniotes, however, the archinephric duct has become a true vas deferens, and is used only for conducting sperm, never urine. As in cartilaginous fish, the upper part of the duct forms the epididymis. In many species, the vas deferens ends in a small sac for storing sperm.[19]

The only vertebrates to lack any structure resembling a vas deferens are the primitive

jawless fishes, which release sperm directly into the body cavity, and then into the surrounding water through a simple opening in the body wall.[19]

Additional images

  • Male reproductive system.
    Male reproductive system.
  • Coronal section of pelvis, showing arrangement of fasciae. Viewed from behind.
    Coronal section of pelvis, showing arrangement of fasciae. Viewed from behind.
  • The relations of the femoral and abdominal inguinal rings, seen from within the abdomen. Right side.
    The relations of the femoral and abdominal inguinal rings, seen from within the abdomen. Right side.
  • The spermatic cord in the inguinal canal.
    The spermatic cord in the inguinal canal.
  • Fundus of the bladder with the vesiculae seminales.
    Fundus of the bladder with the vesiculae seminales.
  • Vertical section of bladder, penis, and urethra.
    Vertical section of bladder, penis, and urethra.
  • Prostate with seminal vesicles and seminal ducts, viewed from in front and above.
    Prostate with seminal vesicles and seminal ducts, viewed from in front and above.
  • Prostate
    Prostate
  • Microscopic cross section.
    Microscopic cross section.
  • Testis, spermatic vessels and vas deferens
    Testis, spermatic vessels and vas deferens
  • A deep dissection showing the vas deferens.
    A deep dissection showing the vas deferens.

See also

This article uses anatomical terminology.

References

  1. S2CID 245049526
    .
  2. ^
    OCLC 1201341621.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link
    )
  3. PMID 11753468
    .
  4. S2CID 81721236
    .
  5. ^ Public domain One or more of the preceding sentences incorporates text in the public domain from page 615 of  the 20th edition of Gray's Anatomy (1918)
  6. ^
    PMID 20074819
    .
  7. PMID 12600736 – via Elsevier
    .
  8. S2CID 4761228
    .
  9. S2CID 7457415
    .
  10. PMID 18787034
    .
  11. ^ Mann, T (1954). The Biochemistry of Semen. London: Methuen & Co; New York: John Wiley & Sons. Retrieved November 9, 2013.
  12. PMID 24683020
    .
  13. PMID 11098022
    .
  14. ^ Sjöstrand, N.O. (1965). "The adrenergic innervation of the vas deferens and the accessory male genital organs". Acta Physiologica Scandinavica. 257: S1–82.
  15. S2CID 95411
    .
  16. S2CID 4303337
    .
  17. PMID 9279805
    .
  18. PMID 12068045
    .
  19. ^
    ISBN 978-0-03-910284-5
    .
  20. ISBN 978-0-643-06257-3
    .
  21. ISBN 978-1-139-45742-2
    .

External links

Wikimedia Commons has media related to Vas deferens.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Vas_deferens&oldid=1204985977"