The gonads are the precursors of the genitalia in males that mostly include external (penis, scrotum, epididymis, and testes) and in females that mainly include internal (vagina, uterus, fallopian tubes, cervix, and ovary) organs; genitalia allow males and females to mate, fertilize internally, and support the growth and development of offspring. 

Testosterone causes undeveloped tissues to differentiate into male sexual organs. When testosterone is absent, the tissues develop into female sexual tissues. Primitive gonads become the genitalia, testes or ovaries. Tissues that produce a penis in males produce a clitoris in females. The tissue that will become the scrotum in a male becomes the labia in a female; that is, they are homologous structures.

Most of the male reproductive system is located outside of the body (external structures) and includes penis, scrotum, epididymis, and testes. The internal organs or the accessory organs include the vas deferens, seminal vesicles, prostate gland, and bulbourethral glands.

External structures:

• Penis: The male organ for sexual intercourse and urination. It delivers urine.
• Scrotum: A loose, pouch-like sack of skin that hangs behind the penis, containing the testes. It carries and supports testes.
• Epididymis: Located at the back of the testis and connects it to the vas deferens. This is where the sperm fully matures and becomes motile, and it functions to store and carry sperm.
• Testis: The location for testosterone production. The coiled collection of tubes within the testes are the seminiferous tubules. Within these tubules, spermatogenesis takes place.

Internal structures:

• Vas deferens: Transports mature sperm to the urethra in preparation for ejaculation.
• Seminal vesicles: Sac-like pouches that attach to the vas deferens near the base of the bladder. It contributes to semen production.
• Prostate gland: A walnut-sized structure located below the urinary bladder in front of the rectum. It also contributes to semen production.
• Bulbourethral (Cowper’s) glands: Pea-sized structures located on the sides of the urethra just below the prostate gland. These glands produce a clear, slippery fluid that cleans urethra at ejaculation.

The functions of the male reproductive system include producing and transporting sperm, ejaculating sperm into the female reproductive tract, and producing and secreting male hormones.

The organs of the male reproductive system are specialized for three primary functions:

1. To produce, maintain, transport, and nourish sperm (the male reproductive cells) and protective fluid (semen).
2. To discharge sperm within the female reproductive tract.
3. To produce and secrete male sex hormones.

Consequently, several reproductive structures are exterior to the female’s body. These include the breasts and the vulva, which consists of the mons pubis, clitoris, labia majora, labia minora, and the vestibular glands. Internal female reproductive structures include ovaries, oviducts, the uterus, and the vagina.

External structures:

• Mons pubis: A round, fatty area that overlies the pubic symphysis.
• Clitoris: A structure with erectile tissue that contains a large number of sensory nerves and serves as a source of stimulation during intercourse.
• Labia majora: A pair of elongated folds of tissue that run posterior from the mons pubis and enclose the other components of the vulva. It covers the labia minora
• Labia minora: Thin folds of tissue centrally located within the labia majora and covers vestibule.
• Greater vestibular glands: Found at the sides of the vaginal opening and provide lubrication during intercourse.
• Breast: Consists of mammary glands and fat. It produces and delivers milk.

Internal structures:

• Ovaries: Held in place in the abdominal cavity. They carry and develop eggs.
• Oviducts or Fallopian tubes: Extend from the uterus in the lower abdominal cavity to the ovaries, but they are not in contact with the ovaries. They transport eggs to the uterus.
• Uterus: A structure about the size of a woman’s fist. It supports the developing embryo and fetus during gestation. The cervix is the lowermost portion of the uterus. 
• Vagina: A muscular tube that serves as a common tube for intercourse, birth canal, and passing menstrual flow.

The human female reproductive system (or female genital system) contains two main parts and functions differently:

Uterus

• Hosts the developing fetus
• Produces vaginal and uterine secretions
• Passes the anatomically male sperm through to the fallopian tubes

Ovaries

• Produce the anatomically female egg cells.
• Produce and secrete estrogen and progesterone

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Key Points

• Primitive gonads become the genitalia, testes or ovaries; tissues that produce a penis in males produce a clitoris in females while the scrotum in a male becomes the labia in a female; that is, they are homologous structures.

• The functions of the male reproductive system include producing and transporting sperm, ejaculating sperm into the female reproductive tract, and producing and secreting male hormones.

• The female reproductive system contains two main parts: the uterus, which hosts the developing fetus, produces vaginal and uterine secretions, and passes the anatomically male sperm through to the fallopian tubes; and the ovaries, which produce the anatomically female egg cells.

• Most of the male reproductive system is located outside of the body that includes the penis, scrotum, epididymis, and testes; internal organs or the accessory organs include the vas deferens, seminal vesicles, prostate gland, and bulbourethral glands.

• A female’s internal reproductive organs are the vagina, uterus, fallopian tubes, cervix, and ovary; external structures include the mons pubis, pudendal cleft, labia majora and minora, vulva, Bartholin’s gland, and the clitoris.

Key Terms

Semen contains spermatozoa, proteolytic and other enzymes, and fructose that promotes spermatozoa survival. It also provides a medium for sperm motility

Testosterone: a steroid hormone produced primarily in the male testes and responsible for the development of male secondary sex characteristics

Vulva: consists of the female external genital organs

Primitive Gonads: formed by the proliferation of germ cells

Genitalia: a sex organ