The vas deferens, also called ductus deferens, is part of the male reproductive system of many vertebrates; these ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. It is a partially coiled tube that exits the abdominal cavity through the inguinal canal.

1. M E M O O N A A R S H A D G R O U P 1 1
P R E S E N T E D T O :
S I R M A R R A T
Vas Deferens

2. Male Anatomy

3. Vas Deferens
 The vas deferens, also called ductus deferens, is part
of the male reproductive system of many vertebrates;
these ducts transport sperm from the epididymis to
the ejaculatory ducts in anticipation of ejaculation. It
is a partially coiled tube which exits the abdominal
cavity through the inguinal canal.

4. Structure
 There are two ducts, connecting the left and
right epididymis with the seminal vesicles to form
the ejaculatory duct in order to move sperm.
 In humans, each tube is about 30 centimeters (1 ft)
long, 3 to 5 mm (0.118 to 0.197 inches) in diameter
and is muscular (surrounded by smooth muscle).
 Its epithelium is pseudostratified columnar
epithelium lined by stereocilia.
 They are part of the spermatic cords.

5. Structure (Contd..)
 Blood Supply
 The vas deferens is supplied by an accompanying artery (artery
of vas deferens). This artery normally arises from
the superior (sometimes inferior) vesical artery, a branch of
the internal iliac artery.

6. Structure (Contd..)

7. Function
 During ejaculation, the smooth muscle in the walls of
the vas deferens contracts reflexively, thus propelling
the sperm forward.
 This is also known as peristalsis.
 The sperm is transferred from each vas deferens into
the urethra, partially mixing with secretions from the
male accessory sex glands such as the seminal
vesicles, prostate gland and the bulbourethral
glands, which form the bulk of semen.

8. Clinical Signification
 Contraception
 The procedure of deferentectomy, also known as a vasectomy,
is a method of contraception in which the vasa deferentia are
permanently cut, though in some cases it can be reversed.
 A modern variation, which is also known as a vasectomy even
though it does not include cutting the vas, involves injecting an
obstructive material into the ductus to block the flow of sperm.
 Investigational attempts for male contraception have focused
on the vas with the use of the intra vas device and reversible
inhibition of sperm under guidance.

9. Clinical Signification (Contd..)
 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), microsurgical
epididymal sperm aspiration (MESA), or other methods of
collecting sperm cells directly from the testicle or epididymis.

10. Clinical Signification (Contd..)
 Uses in pharmacology and physiology
 The vas deferens has a dense sympathetic innervation, making
it a useful system for studying sympathetic nerve function and
for studying drugs that modify neurotransmission.
 It has been used:
 as a bioassay for the discovery of enkephalins, the endogenous
opiates.
 to demonstrate quantal transmission from sympathetic nerve
terminals.
 as the first direct measure of free Ca2+ concentration in a
postganglionic nerve terminal.
 to develop an optical method for monitoring packeted
transmission (similar to quantal transmission).

11. Other Animals
 Most vertebrates have some form of duct to transfer
the sperm from the testes to the urethra.
In cartilaginous fish and amphibians, sperm is
carried through the archinephric duct, which also
partially helps to transport urine from the kidneys.
 In teleosts, there is a distinct sperm duct, separate
from the ureters, and often called the vas deferens,
although probably not truly homologous with that in
humans.
 The vas deferens loops over the ureter in placental
mammals, but not in marsupial mammals.

12. Other Animals (Contd..)
 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.

13. Other Animals (Contd..)
 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.
 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.

14. Other Animals (Contd..)