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The Male Reproductive System

15 THE MALE REPRODUCTIVE SYSTEM

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Introduction

I n simple terms, reproduction is the process by which organisms create descendants. This miracle is a

characteristic that all living things have in common and sets them apart from nonliving things. But
even though the reproductive system is essential to keeping a species alive, it is not essential to keeping
an individual alive.

In human reproduction, two kinds of sex cells or gametes are involved. Sperm, the male gamete,
and an egg or ovum, the female gamete must meet in the female reproductive system to create a new
individual. For reproduction to occur, both the female and male reproductive systems are essential.

While both the female and male reproductive systems are involved with producing, nourishing and
transporting either the egg or sperm, they are different in shape and structure. The male has
reproductive organs, or genitals, that are both inside and outside the pelvis, while the female has
reproductive organs entirely within the pelvis.

The male reproductive system consists of the testes and a series of ducts and glands. Sperm are
produced in the testes and are transported through the reproductive ducts. These ducts include the
epididymis, ductus deferens, ejaculatory duct and urethra. The reproductive glands produce secretions
that become part of semen, the fluid that is ejaculated from the urethra. These glands include the
seminal vesicles, prostate gland, and bulbourethral glands.

Structure

Testes

The testes (singular, testis) are located in the scrotum (a sac of skin between the upper thighs). In
the male fetus, the testes develop near the kidneys, then descend into the scrotum just before birth.
Each testis is about 1 1/2 inches long by 1 inch wide. Testosterone is produced in the testes which
stimulates the production of sperm as well as give secondary sex characteristics beginning at puberty.

Scrotum

The two testicles are each held in a fleshy sac called the scrotum. The major function of the scrotal
sac is to keep the testes cooler than thirty-seven degrees Celsius (ninety-eight point six degrees
Fahrenheit). The external appearance of the scrotum vaires at different times in the same individual
depending upon temperature and the subsequent contraction or relaxation of two muscles. These two
muscles contract involuntarily when it is cold to move the testes closer to the heat of the body in the
pelvic region. This causes the scrotum to appear tightly wrinkled. On the contrary, they relax in warm
temperatures causing the testes to lower and the scrotum to become flaccid. The temperature of the
testes is maintained at about thirty-five degrees Celsius (ninety-five degrees Fahrenheit) below normal

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