Читать книгу Ridley's The Vulva - Группа авторов - Страница 117
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ОглавлениеChanges through life Neonate Childhood Puberty Reproductive years Sexual response Pregnancy Menopause
The main roles of the vulval epithelium are to provide a barrier function and to regulate an immune response. There are variations at different sites and at different times during life, with hormonal alterations being the predominant influence [1]. These normal changes can also be modified by oral contraceptives and hormone replacement therapy.
The principal hormones involved in these changes are oestrogens, progestogens, and small amounts of androgens. Oestrogen has many effects on skin and mucosa [2]. It increases support by thickening the collagen, hydrates by increasing mucopolysaccharides and hyaluronic acid, and also stimulates melanogenesis. The effects of progesterone are not so well understood, but this hormone is known to increase vascularity and sebum secretion.
Immunohistochemical studies have identified receptors for these hormones at different sites within human skin [3]. Further studies in the female genital skin have mapped out their distribution in the vulva and vagina, showing variation with different stages of the menstrual cycle [4], with oral contraceptive use [5], and at menopause [6]. Oestrogen receptors are mainly found in the labia minora and vagina. Androgen receptors are most commonly seen in the keratinocytes of the labia majora as well as the adnexal structures and fibroblasts. Progesterone receptors were found only on vaginal epithelium and inner labia minora. There is little difference in this distribution before and after menopause.
