Urethra. An opening into the vestibule anterior to the vaginal introitus. The canal is lined by transitional epithelium with stratified squamous epithelium at the orifice. The muscularis is composed of a longitudinal inner layer and a circular outer layer of smooth muscle.
Skene's ducts are located in the floor of the terminal end of the urethra and open just within or external to the meatus. They are 0.5 to 1.5 cm long.
Labia majora. Form the lateral boundaries of the vulva. They are composed of folds of adipose and fibrous tissue. They fuse anteriorly into the mons pubis. Posteriorly they terminate 3-4 cm anterior to the anus where they are united by the posterior commissure or fourchette. Histologically, the skin contains an outer lining of stratified squamous epithelium. This consists of a basal layer of cells (stratum malpighii), a thin granular layer, and a horny layer.
Labia minora. Consist of two folds of connective tissue which contain little or no adipose tissue. Anteriorly, the labia minora divide into two parts. One part passes over the clitoris to form the prepuce. The other joins beneath the clitoris and forms the frenulum. Posteriorly, they blend with the medial surfaces of the labia majora. The skin and mucosa of the labia minora are rich in sebaceous glands. The deeper area contains dense connective tissue.
Bartholin's gland (H&E x25). The Bartholin's gland corresponds to the bulbourethral glands in the male. The duct is lined with transitional epithelium. The peripheral acini are single-layered columnar cells with clear cytoplasm.
Sebaceous glands (H&E x25). Sebaceous glands can be seen along the inner aspect of the labia minora, clinically appearing as small raised papules (Fordyce spots). They are not associated with hair follicles.
The Vestibule: (General Comments) The vestibule is the area between the hymen and Hart's line. It is lined by non-keratinized squamous epithelium. Structures found in the vestibule include the major vestibular (Bartholin's) glands, the minor vestibular glands, the periurethral (Skene's) glands, and the urethra.
Vestibule-nonkeratinized squamous epithelium (H&E x25). The squamous cells are well glycogenated and resemble the vaginal or cervical squamous cells. Skin adnexa are not present.
Vestibule-minor vestibular glands (H&E x25). The minor vestibular glands (corresponding to the penile glands of Littre) are concentrically located within the vestibule. They usually average between 2 and 10 glands per specimen. They are shallow glands (extending no deeper than 3 mm into the underlying dermis) lined by a single layer of mucin secreting columnar cells. They open directly onto the surface.
Vestibule-minor vestibular clefts (H&E x25). When inflamed, the minor vestibular glands heal by squamous metaplasia. Over time, small clefts form in the site where minor vestibular glands previously existed.
Glands. Apocrine glands (scent glands) develop their secretory function at adrenarche. The apocrine glands of the vulva are identical to those of the axillae, breast and perianal regions. The height of the secretory cells varies. The lumina of the glands are large when compared to the lumina of eccrine glands.
Eccrine glands (sweat glands) are primarily involved in heat regulation. They function before puberty. They are lined by a layer of epithelial cells that contain an eosinophilic cytoplasm.
Sebaceous glands are alveolar, holocrine glands which do not contain lumina. Each gland is composed of several lobules. The cells in each lobule form a delicate network filled with fat.
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