Comparative ultrastructure and cytochemistry of epidermal responses to tape stripping, ethanol and vitamin A acid in hairless mice.

The responses of hairless mouse epidermis to tape stripping, ethanol and vitamin A acid were compared using electron microscopy and cytochemistry. Stripping the skin 4 times with cellophane tape removed most of the stratum corneum and caused the development of enlarged intercellular spaces and dense intramitochondrial inclusions. These changes began within an hour, reached a maximum by 24 hr, and subsided by about 4 days. There was also some accumulation of glycogen and the development of occasional basal lamina breaks and a few intracellular lipid droplets by 24 hr. Topically applied ethanol (95%) produced a similar response, though less damaging. In addition, ethanol induced the formation of numerous lipid droplets in the cytoplasm of keratinocytes by 24 hr and often caused sloughing of the stratum corneum. Vitamin A acid (3%) was dissolved in propylene glycol for application to the skin. We found the application of propylene glycol alone to produce no epidermal changes. Vitamin A acid produced mild damaging effects with small intercellular spaces and intramitochondrial inclusions, but no lipid droplets or glycogen were detected. Vitamin A acid also caused dramatic inhibition of keratinization by 24 hr. Intramitochondrial inclusions were digested by protease, indicating a protein component and they also stained with silver methenamine, indicating the presence of glycogen or glycoprotein.