Objective: To map potential sites of sex steroid action in the human vulva.
Methods: Monoclonal antibodies to androgen, oestrogen and progesterone receptors were used to stain frozen sections of vulval skin, vagina and suprapubic skin. A scoring system was devised to compare receptor distribution in the epidermis and dermis of skin with vaginal epithelium and stroma.
Results: Androgen receptors were seen in epidermal keratinocytes, sebaceous glands, sweat glands, hair follicles and dermal fibroblasts of skin, and epithelial cells and stromal fibroblasts of the vagina. Androgen receptor scores were significantly higher in the epidermis of labia majora and minora than in vaginal epithelium. Oestrogen receptors were seen in basal and suprabasal cells of vaginal epithelium and epidermis of labia minora but were restricted to basal keratinocytes in true skin. They were seen in stromal fibroblasts and vaginal smooth muscle, and dermal fibroblasts of the skin. Oestrogen receptors were highest in vaginal epithelium and stroma, and lowest in suprapubic skin. Progesterone receptors were seen in vaginal epithelium, fibroblasts and smooth muscle but not in the vulva. There was no evidence of significant differences in androgen or oestrogen receptor staining in the vulva of pre- or postmenopausal women.
Conclusion: The transition from vagina to vulva is marked by an increase in androgen and a decrease in oestrogen and progesterone receptors. This distribution of receptors would indicate a limited role for oestrogen creams on the vulva.