b. Epididymis. At the upper and posterior part of each testis is the epididymis--
an elongated, triangular tube which is 16 to 20 feet in length. Each comma-shaped tube
is positioned along the posterior side of a testis and is mostly made up of a tightly coiled
tube called the ductus epididymis. Sperm mature in the epididymis tubes. These tubes
link the testes proper with the ductus deferens. Sperm are stored in the epididymis
tubes until they are ejaculated and enter the vas deferens.
c. Ductus (Vas) Deferens. At its tail, the epididymis becomes less coiled, its
diameter increases, and the tubes become known as the ductus deferens or the vas
deferens. Ductus deferens are muscular tubes which are about 48 centimeters (18
inches) long. Two ductus deferens, one from each epididymis tube, lead up through the
inguinal canal into the pelvic cavity, cross to the posterior surface of the urinary bladder,
and unite with the ducts of the seminal vesicles to form the ejaculatory ducts. Each
ductus deferens stores sperm for a period of up to several months and propels sperm
toward the urethra during ejaculation.
d. Seminal Vesicles. The seminal vesicles are two glandular pouches located
behind and below the urinary bladder. These tubular structures secrete a fluid which
activates the spermatozoa in the semen. The secretions contain sugar fructose and
prostaglandins. Fructose energizes the sperm, and prostaglandins assist ejaculation
and stimulate uterine contractions. Thus, both fructose and prostaglandins help sperm
move to the uterine tubes where fertilization occurs. Additionally, this fluid is slightly
alkaline, which helps protect sperm against the acid secretion of the vagina. Secretion
of the seminal vesicles makes up 60 percent of the ejaculate (fluid ejaculated).
e. Ejaculatory Duct. Each ductus deferens and its corresponding seminal
vesicle come together to form a short tube called the ejaculatory duct. The ejaculatory
duct opens into the urethra within the prostate gland. The ejaculatory duct carries both
sperm and seminal vesicle fluid.
f. Prostate Gland. This gland is a single, doughnut-shaped gland which is
about the size of a chestnut. The gland lies directly below the urinary bladder and
surrounds the prostatic part of the urethra. The prostate gland secretes a highly
alkaline fluid which protects sperm acidity in the urethra and vagina. Secretion from the
prostate gland is added to the sperm and seminal vesicle fluid. From 13 to 33 percent
of the volume of semen seminal vesicle fluid is prostate gland secretion. Prostate gland
secretion also contributes to sperm motility.
g. Bulbourethral (Cowper's) Glands.
(1) Description/information. These are two small glands, about the size of
peas, located just below the prostate on either side of the urethra. These glands
secrete a mucous-like lubricating fluid into the membranous urethra. The glands also
secrete a substance that neutralizes urine. Ducts of these glands open into the spongy