The vagina is the passage that leads from the uterus above to open at the vulva below. It is approximately three to four inches in length and widens at its upper end to be attached round the cervix which is the neck of the uterus. The wall of the vagina is a muscular tube capable of considerable stretching. It is lined on the inside by the vaginal skin which covers the cervix above the vulva below. Because the vagina is a distensible organ and the vaginal muscular wall is capable of considerable stretching, the vaginal skin is thrown up into folds or ridges and extra skin allows the organ to stretch when required. This particular property is utilized during sexual intercourse and especially during labor, when the baby's head passes down the vagina. The skin of vagina entrance is pinched up to form the hymen (a fold which partly seals the entrance).

The hymen varies considerably in shape and in size but even in the young it usually has a small opening through which the menstrual blood may pass. Many girls find that the opening is large enough for them to use internal tampons but in others it is too small to allow them to use this modern advance in female hygiene. The hymen may be ruptured or simply stretched during the first act of sexual intercourse. If it is ruptured there may be a small amount of bleeding which is unlikely to be severe and usually ceases spontaneously within a few minutes or a few hours. If it is lacerated or torn, the hymen itself and the vaginal entrance are sore and tender until the injuries heal. Sexual intercourse may then cause discomfort or actual pain for one or two days and it is unwise for a woman to have intercourse again until the lacerations have healed. Painful intercourse does not give any pleasure and as a result a woman may easily develop an actual dislike for intercourse. Many instances of true frigidity can be traced to painful sexual intercourse, especially that which follows rupture of the hymen.

On rare occasions, there is no opening in the hymen. This condition is known as imperforate hymen and although the girl commence to menstruate, the menstrual blood is dammed up in the vagina for several months until such time as the hymen either ruptures spontaneously or is opened surgically.

The vagina is normally and naturally moist. The moisture is secreted from the cervix and walls of the vagina and forms a natural lubrication. It should not be sufficiently profuse to constitute a vaginal discharge.

Bartholin's glands are situated one at each side of the vaginal entrance and they respond to sexual stimulation by a dramatic increase in their secretion. Sexual excitement results in a rapid increase in all the vaginal secretions, but those coming directly from Bartholin's glands are the most profuse and important.