Читать книгу Ridley's The Vulva - Группа авторов - Страница 97

The vulva is covered in epithelia that gradually change from normal keratinised skin on the outer aspects to a non‐keratinised mucosa in the vestibule and vagina.

Keratinised, stratified squamous epithelium is made up of four layers histologically:

1 A basal layer, the lower border of which rests on the basal lamina

2 A spinous or prickle‐cell layer, which forms the bulk of the epidermis

3 A granular layer

4 A horny layer or stratum corneum.

The epithelial thickness reduces and the keratin layer increases going from medial to lateral on the vulva [29]. This has been confirmed in a recent study of 118 biopsies of normal vulval skin [30]. In addition, it was found that the stratum corneum was always of a basket weave pattern on the mons pubis, and this pattern was more common in hair‐bearing skin but did not occur on the perineum, where compact or intermediate patterns were seen.

Differentiation is the process that occurs as the keratinocytes move upwards through the spinous layers to form the tough, protective, flexible outer surface of the skin. The keratinocytes flatten and lose their nuclei as they progress upwards, ending up as flattened structureless squamous cells at the surface. Parakeratosis (the retaining of nuclei) can be seen at the mucocutaneous junction in some patients and is considered a normal finding [30].