American Medical Association Family Medical Guide - American Medical Association [547]
The prostate gland, Cowper’s glands, and seminal vesicles produce fluids that support sperm and make up about 98 percent of semen. When a male is sexually aroused, spongy tissue inside the penis fills with blood, causing the penis to become erect. During an orgasm, semen is ejaculated through the urethra (a muscular tube inside the penis that carries urine and semen out of the body). The muscular action of ejaculation automatically closes the neck of the bladder, temporarily preventing urine from entering the urethra and preventing semen from entering the bladder.
Infections of the reproductive and urinary tracts are rare in men because the length of the urethra usually provides an effective barrier against infectious agents. However, because the organs of the reproductive system are connected to the organs of the urinary tract, a disorder in one system can cause symptoms in the other.
Disorders of the Testicles and Scrotum
The testicles develop inside the abdomen of a male fetus. By the time the baby is born, the testicles have usually descended through the abdominal wall and are suspended inside a pouch of skin and muscle called the scrotum. Each testicle is connected to the body by a single spermatic cord, which is composed of the vas deferens (sperm duct), nerves, and blood vessels.
Sperm are collected and stored in the epididymis (a tightly coiled tube that lies above and behind each testicle) until they mature (which takes about 3 weeks). Fully developed sperm pass into the vas deferens, where they are stored. During orgasm, sperm travel from the vas deferens to the seminal vesicles, where they mix with fluids produced by the prostate gland, Cowper’s glands, and seminal vesicles to form semen. Semen is ejaculated from the body through the urethra. Sperm that are not ejaculated in semen during orgasm gradually break down and are reabsorbed by the body.
Cross section of a testicle and scrotum
Cancer of the Testicle
Cancer of the testicle (or testicular cancer) is a growth of malignant cells inside a testicle. Although testicular cancer accounts for only about 1 percent of all cancers in men, it is the most common form of cancer in men between ages 18 and 35. In the United States, 6,000 to 8,000 cases of testicular cancer are diagnosed each year. Cancer of the testicle occurs more often in whites than in people of other races. Advances in the development of new drugs and diagnostic tests have significantly increased the survival rates of people with testicular cancer. With early diagnosis and treatment, cancer of the testicle is frequently curable.
The two different types of testicular cancer are seminomas (which account for about 35 to 40 percent of cases) and nonseminomas (which account for about 60 percent of cases). Seminomas consist of a single type of immature germ cell that probably arises from the cells that produce sperm. Because seminomas tend to grow slowly, they are usually detected before they spread to other parts of the body. Nonseminomas consist of a mix of different types of cells. Because nonseminomas tend to grow more rapidly, they often spread to other parts of the body before they are detected. An estimated 60 to 70 percent of men who are diagnosed with nonseminomas have cancer that has spread to nearby lymph nodes.
The risk of developing testicular cancer is increased in men who were born with undescended testicles—a condition called cryptorchidism (see page 431). That risk rises if cryptorchidism is not corrected surgically before