An examination of excised skin tissues used for in vitro membrane permeation studies

The morphology and layer thicknesses of excised human and hairless mouse skin have been examined. Excised tissues were prepared either by heating at 60°C or by incubation in an ethylenediamine-tetracetic acid (EDTA) solution. Either process yielded spearated sheets of stratum corneum plus attached viable epidermis (SCE), the thicknesses of which were determined microscopically. These measurements indicated that initial skin separation occurred at the dermal/epidermal junction for both separation processes. The two techniques produced SCE sections showing consistent differences in thickness of the attached viable epidermis layer. This effect depended upon the presence or absence of epidermal invaginations. In the former case, EDTA-separated tissue gave narrower viable epidermis of more uniform thickness than that seen with heat-separated tissue. In the latter case, both techniques produced SCE having viable epidermis layers of similar thickness.