The Vulva

Abstract

The external female genitalia include the mons pubis, the labia majora and minora, the clitoris with its prepuce and frenulum, and the vestibule into which open the orifices of Skene’s and Bartholin’s glands and the urethral meatus (Figure 2.1). All of these structures are easily visualized except for the Bartholin gland orifices, which are normally not seen unless inflamed. With adrenarche, the mons pubis and lateral aspects of the labia majora acquire increased amounts of subcutaneous fat and develop the coarse curly surface hair characteristic of the adult. With maturation of the hair follicle apparatus, there is concomitant maturation and development of the sebaceous and apocrine glands in the hair-bearing regions and also in the labia minora and inner aspect of the prepuce. Other than the areola of the breast, these are the only areas where sebaceous glands routinely develop without concomitant hair formation (Figure 2.2). During adolescence, the labia acquire a characteristic hyperpigmentation and the clitoris undergoes some selective enlargement. The labia majora contain both smooth muscle and fat, whereas the labia minora are devoid of adipose tissue but are rich in elastic fibers and blood vessels. The entire vulva is covered by a keratinized, stratified squamous epithelium. Medially as the vaginal introitus is approached, this epithelium becomes thinner, the rete ridges less prominent, and the keratin layer less pronounced. The hymen is thinly keratinized on its external surface but on the vaginal surface shows a nonkeratinized mucous membrane that is rich in glycogen. The epithelium of the vestibule merges with transitional epithelium at the urethral meatus and the duct openings of the Bartholin glands.