Vulva

The vulva is not a particular organ, but a series of outer folds that protect the vagina. These external genital formations include the mons pubis, the outer and inner lips (labia majora and minora), the clitoris, hymen, vestibule, and urethra, and two pairs of lubricating glands.

Except for the round, plump mons pubis, all these sexual structures are well hidden. The distribution of curly pubic hair over the mons can sometimes provide a clue to fertility problems. For example, the usual pattern of pubic hair is an inverted triangle, with the top forming a nearly straight line across a woman's stomach. (Only in Asian women, who typically have less pubic hair, is the line less defined.) If the pattern is more diamond shaped, with hair growth pointing toward the navel, as it does in men, it suggests an increase of male hormone production.

Every woman normally produces a certain amount of the male hormone testosterone, and possessing a little extra is probably the result of genetic happenstance. The excess doesn't affect a woman's femininity or her sexual preference, although she may have a stronger sex drive. But it can affect her fertility. Excess male hormone, as we will see later, may interfere with ovulation and cause infertility.

Labia Majora

Lying along either side of the vaginal entrance, and merging at the top into the mons pubis, are two large, round pads. These are the labia majora, or large lips, which are analogous to the scrotum of the male. If the labia majora could be pulled forward and two testicles placed inside, the result would be a scrotum. The labia majora are firm and covered with pubic hair. As a woman ages, the fat pads under the skin thin out and the lips become more flaccid.

The labia majora contain sebaceous glands that produce sweat and oil around the hair follicles. These firm lips cover the vaginal opening and protect against infection and disease.

Labia Minora

When the large lips are pulled back, the smaller inner folds of the labia minora are exposed. There is no pubic hair on these lips; they fold over the vagina, completely sealing the entrance from invasion by any bacteria lingering around the labia majora. At the top, the small lips form a small tent over the urethra, directing the stream of urine downward.

These small lips, whose upper portion surround the clitoris, are the equivalent of the uncircumcised foreskin in a man. They are highly erotic and sensitive, responding easily to sexual stimulation. During sexual arousal, the veins of the labia minora constrict, and blood rushing into them cannot flow out. The engorged lips grip the penis; this gripping action also helps prevent semen from spilling out of the vaginal vault after a man ejaculates.

Sebaceous glands in the labia minora release a white lubricant, just as the male foreskin does. Some of this soapy discharge, called smegma, is released every day and, unless washed away daily, can irritate and in flame the skin.

In childhood the small lips are completely hidden by the bigger labia majora. But as a girt enters womanhood, the inner lips begin to grow larger and eventually extend past the large lips. In the recent past male physicians had the notion that relatively large labia minora proved that a woman was a chronic masturbator. And, they suggested, such a woman was, if not emotionally disturbed, then certainly morally corrupt. Physi cians today are usually more knowledgeable. Masturbation in both sexes is normal. If anything, masturbation increases sexual sensitivity and improves other sexual pleasures. As far as the female anatomy is concerned, masturbation has little effect on the size of the labia. To increase the size of the inner lips, a woman would have to masturbate strenuously and repeatedly for several decades.

There are, of course, normal variations in the size of the labia minora, mainly determined by genetic factors. Just as genes determine physical height and the size of the nose, so do they determine the size of the sexual organs in both men and women. Strong manipulation and intense sexual activity stretch the small lips to some extent; childbirth may also enlarge them. (Only rarely are the labia minora so large that they interfere with sexual pleasure. In these instances the excess flap of skin can be removed surgically.)