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The Merck Manual--Second Home Edition logo
 
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Chapter 241. Biology of the Female Reproductive System
Topics: Introduction | External Genital Organs | Internal Genital Organs | Puberty | Menstrual Cycle | Effects of Aging
 
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External Genital Organs

The external genital organs consist of the mons pubis, labia majora, labia minora, Bartholin's glands, and clitoris. The area containing these organs is called the vulva. The external genital organs have three main functions: enabling sperm to enter the body, protecting the internal genital organs from infectious organisms, and providing sexual pleasure.

click here to view the figure See the figure External Female Genital Organs.

The mons pubis is a rounded mound of fatty tissue that covers the pubic bone. During puberty, it becomes covered with hair. The mons pubis contains oil-secreting (sebaceous) glands that release pheromones, which are involved in sexual attraction. The labia majora (literally, large lips) are relatively large, fleshy folds of tissue that enclose and protect the other external genital organs. They are comparable to the scrotum in males. The labia majora contain sweat and sebaceous glands, which produce lubricating secretions. After puberty, hair appears on the labia majora.

The labia minora (literally, small lips) can be very small or up to 2 inches wide. The labia minora lie just inside the labia majora and surround the openings to the vagina and urethra. A rich supply of blood vessels gives the labia minora a pink color. During sexual stimulation, these blood vessels become engorged with blood, causing the labia minora to swell and become more sensitive to stimulation.

The area between the vaginal opening and the anus, at the back of the labia majora, is called the perineum. It varies in length from almost 1 to more than 2 inches (2 to 5 centimeters). A long perineum is less likely to tear during childbirth.

The labia majora and the perineum are covered with skin similar to that on the rest of the body. The skin is thick, dry, and sometimes scaly. In contrast, the labia minora are lined with a mucous membrane, whose surface is kept moist by fluid secreted by specialized cells.

The opening to the vagina is called the introitus. The vaginal opening is the entryway for the penis during sexual intercourse and the exit for menstrual blood and vaginal discharge as well as a baby. When stimulated, Bartholin's glands (located beside the vaginal opening) secrete a thick fluid that supplies lubrication for intercourse. The opening to the urethra, which carries urine from the bladder to the outside, is located above and in front of the vaginal opening.

The clitoris, located between the labia minora, is a small protrusion that corresponds to the penis in the male. The clitoris, like the penis, is very sensitive to sexual stimulation and can become erect. Stimulating the clitoris can result in an orgasm.

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