Male Genitals.

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. It is very sensitive to stimulation, and it is the organ that penetrates the vagina or anus during penetrative sex. The head of the penis, the glans (glans penis), includes the most highly innervated part of the penis and is covered by the foreskin in men who are not circumcised. The penis provides passage for both urine and semen. 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 by the testes.

Internal Male Genitals.

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 posterior side of the testes where sperm mature and are stored until they are released during ejaculation. The vasa deferentia (singular, vas deferens) 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.Cowper’s glands are two pea-sized glands at the base of the penis under the prostate that secrete a clear alkaline fluid into the urethra during sexual arousal and before orgasm and ejaculation. These glands produce mucoid, 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.