Incorporation of tritiated thymidine, leucine and histidine in murine tail epidermis after skin irritation (histoautoradiography).

Thymidine incorporation into epidermal DNA as well as leucine and histidine incorporation into epidermal protein were studied by histoautoradiography in female mice tail epidermis. Prior to in vitro incubation of skin samples with labelled precursors, tail skin was irritated mechanically by rubbing with fine sand paper, chemically by repeated topical administration of n-hexadecane and by feeding an essential fatty acid deficient diet. After these skin irritations, an increased thymidine labelling index and skin thickening were found. Leucine was shown to be incorporated into protein predominantly in basal epidermal cell layers, while histidine was incorporated predominantly in the granular layer. Especially after mechanical skin irritation, this difference was obvious.