Urethra. An opening into the vestibule anterior to the vaginal introitus. The canal is lined by transitional epithelium with stratified squamous epitheliun 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.
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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.
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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.
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The Vestibule: General Comments
Primarily endodermal in origin, the vestibule is bordered by the clitoris anteriorly, the fourchette posteriorly, medially by the hymeneal remnants, and laterally by the labia minora. It is covered by stratified squamous epithelium, which has a thin keratin layer beyond Hart's line, and is non-keratinized (silmilar to the vagina) between Hart's line and the introitus. Structures found in the vestibule include the major vestibular (Bartholin's) glands, the minor vestibular glands, the periurethral (Skene's) glands, and the urethra.
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Vestibule-keratinized squamous epithelium (H&E x25). A thin layer of keratin covers these squamous cells, reminiscent of the labia majora. Nevertheless, this area lacks hair follicles, eccrine and apocrine glands.
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Vestibule-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.
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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.
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Vestibule-minor vestibular glands (H&E x25). The minor vestibular glands (corresponding to the penile glands of Littre) are concentrically located within the vestibule along Hart's line. 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 into the surface.
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Vestibule-minor vestibular clefts (H&E x25). When infoamed, the minor vestibular glands heal by squamous metaplasia. Over time, small clefts form in the site where minor vestibular glands previously existed.
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