In popular speech the vagina is the entire area of the vagina and vulva: everything pink and soft (mucous tissue) so also the labia (the 'lips') majora (outer) and minora (inner). The inside of the labia majora and all of the labia minora carry many small glands. The secretions of those glands (different from those of the skin) 'coat' this area and form a thin protective layer against urine, bacteria and menstrual blood. On both sides of the vestibulum (the entrance into the vagina) are 2 glands that produce a fluid during sexual excitement and lubricate the vestibulum in preparation of sexual intercourse. The vagina itself is an 8 cm tube which extends from the vestibulum to the cervix (the opening to the womb). On both sides of the cervix the vagina bulges out into a pocket which is called a fornix. In these fornices, especially the one on the backside, secretion of the cervix and some cell-debris may collect.
The vagina itself has no glands but is lubricated by the secretion of the cervix. Normal vaginal discharge has a pleasant, mild smell and looks like a milky white cream or a clear egg white, depending on the moment of the menstrual cycle.
The vagina is covered with a mucous tissue which is protective and rather strong. The thickness of this tissue is determined by the balance of the sex hormones. This balance changes during the menstrual cycle, during pregnancy and with age. In young girls and older women the mucous tissue is only a few cell layers thick. In these women this tissue is therefore quite vulnerable and the balance of the vaginal environment can easily be disturbed.
In the vagina (as well as e.g. in the mouth and the bowels) a great many micro-organisms are living in balance with each other and their hostess. This is called the 'vaginal flora'. It is important to know that the vagina usually has an acidic environment (a low pH). Some women will have heard of Lactobacillus vaginalis as a useful bacterium. Lactobacilli -lactic acid bacteria- are named after their property to produce lactic acid. They largely determine the acidity of the vaginal environment. But also here the rule is valid; too many is too much. In some women we observe too many lactobacilli. When this condition is accompanied by complaints that resemble those caused by candidiasis the diagnosis is called 'Lactobacillosis'.
Typically these women are constantly and, of course without result, treated for candidiasis. Next to lactobacilli (rod shaped bacteria) other bacteria are often present, the cocci (roundish bacteria), that belong to the bowel flora. These are certainly not useful but the presence of a certain number of these cocci is acceptable in a 'healthy vaginal environment' (the mixed flora). When lactobacilli are absent the right protective acidity of the vagina has also disappeared. In this case the vaginal environment has become alkaline (as opposed to acid). This environment promotes overgrowth of coccoid bacteria often resulting in an infection called bacterial vaginosis. In summary we can say that the natural protection of the vagina is determined by several factors; the cel layers of the vaginal mucous, the acidity of the vagina (pH), the balance between the micro-organisms present and the state of general health of the woman. Disturbing the balances in the vagina has some consequences. In the worst cases it can result in infections and inflammations. The disturbances can be caused by external factors as well as factors from within the body (internal factors) or by a combination of both.