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Male Sexual and Reproductive Organs
 External
Male Genitals
The external male genitals
consist of the penis and the scrotum.
The penis is a cylindrical
structure with the capacity to be flaccid or erect. The penis provides
passage for both urine and semen. It can be a source of pleasure in response
to sexual stimulation and is the organ that penetrates the mouth, vagina
or anus during penetrative sex. The head of the penis, the glans
(glans penis), is the part of the penis that is
most sensitive and has the most nerve endings. The glans is covered by
the foreskin, or prepuce, in men who are not circumcised.
The scrotum is a pouch
of skin hanging directly under the penis that contains the testes. The
scrotum protects the testes and maintains the temperature necessary for
the production of sperm.
The internal male genitals are: the testes, the epididymides, the
vasa deferentia, the seminal vesicles, the prostate gland, and the Cowper’s
glands.
The testes, the paired, oval-shaped organs that produce sperm and
male sex hormones, are located in the scrotum. They are highly innervated
and sensitive to touch and pressure. The testes produce testosterone,
which is responsible for the development of male sexual characteristics
and sex drive (libido).
The epididymides are
the two highly coiled tubes against the back side of the testes where
sperm mature and are stored until they are released during ejaculation.
The vasa deferentia
are the paired tubes that carry the mature sperm from the epididymides
to the urethra.
The seminal vesicles
are a pair of glandular sacs that secrete about 60% of the fluid that
makes up the semen in which sperm are transported. Seminal fluid provides
nourishment for sperm.
The prostate gland
is a walnut-sized, glandular structure that secretes about 30% of the
fluid that makes up semen. The alkaline quality of the fluid neutralizes
the acidic environment of the male and female reproductive tracts. A muscle
at the bottom of the prostate gland keeps the sperm out of the urethra
until ejaculation begins. The prostate gland is very sensitive to stimulation
and can be a source of sexual pleasure for some men.
The Cowper’s glands
are two pea-sized glands at the base of the penis under the prostate gland
that secrete a clear alkaline fluid into the urethra during sexual arousal
and before orgasm and ejaculation. These glands produce mucus-like, pre-ejaculatory
fluid in the urethra that acts as a lubricant for the sperm and coats
the urethra as semen flows out of the penis.
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