epididymal wall. During this passage through the epididymis, the spermatozoa become
mature functioning gametes. They remain in the epididymis until "called for."
b. Ductus (Vas) Deferens. During sexual excitement, the spermatozoa leave
the epididymis and are carried by another duct known as the ductus deferens. The
ductus deferens passes through the inguinal canal, enters the body cavity, and turns
into the pelvic cavity.
c. Seminal Vesicle. At the posterior surface of the prostate gland, the ductus
deferens is joined by another duct called the seminal vesicle. The seminal vesicle is
also a long tubular structure, but it is coiled up into a small mass at the back of the
prostate gland. The seminal vesicle produces a nutrient fluid that helps to maintain the
d. Ejaculatory Duct. On each side, as the ductus deferens and seminal vesicle
join, they form a single tube on the same side, called the ejaculatory duct. Each
ejaculatory duct, left and right, carries the seminal vesicle secretion and spermatozoa
through the substance of the prostate gland. Each ejaculatory duct empties into the
e. Prostate Gland. The prostate gland is located in the pelvic cavity
immediately under the urinary bladder. The urethra of the urinary system passes
through the substance of the prostate gland, where it is known as the prostatic urethra.
The prostate gland also adds a secretion. Altogether, the combination of secretions and
spermatozoa is known as the semen.
f. Urethra. In the male, the urethra is common to both the urinary system and
the reproductive system. At different times, it carries either the urine or the semen.
(1) As already mentioned, the initial part of the urethra passes through the
prostate gland and is called the prostatic urethra.
(2) Immediately below the prostate gland, the urethra passes through the
perineal membrane. Here, it is surrounded by the external urethral sphincter. This
short section of the urethra is called the membranous urethra.
(3) That portion of the urethra passing through the penis (discussed below) is
known as the penile urethra.
g. Penis. The penis is a structure attached to the pubic arch of the bony pelvis
and to the underside of the perineal membrane. It is an external structure of the male
genital system, which is capable of enlargement and stiffening (erection).
(1) The most favorable position for the deposit of semen (spermatozoa) is
the upper recess of the vagina. This is opposite the opening of the cervix of the uterus.
For this purpose, the penis is inserted into the female vagina ("sheath").