Epidermal regeneration and percutaneous water loss following cellophane stripping of reptile epidermis

The histological and physiological effects of the removal of superficial corneous epidermal materials have been studied in several squamate species and a caiman. The gross and microscopic anatomy of the squamate integument has characteristics which make cellophane stripping inherently variable, but in general, when corneous materials were removed, they are replaced over a period of one to two weeks, by a tissue with the histological characteristics of the normal alpha-layer. This tissue may be produced by stimulated germinal activity and/or metaplasia of the other presumptive cell populations. In caiman, the thickness of the corneous tissues of the outer scale surface is reduced by stripping and the tissue is restored to normal in approximately two weeks by stimulated germinal proliferation. Measurements of cutaneous water loss (CWL) before, immediately after, and during two weeks post-trauma revealed the following. There is a sudden rise in CWL immediately after stripping, and values decline over the next two weeks as the corneous tissues are replaced. The results are interpreted as indicating that, as in mammals, the impermeability of the epidermis depends on the thickness of the corneous materials. In squamates it appears that the physiological barrier is the alpha-layer of the epidermal generation, and while the beta-layer cannot be excluded as playing some role in reducing the permeability of the integument, its role appears to be primarily mechanical.