Microfluorometric study of nuclear DNA in normal human epidermis

Quantitative and qualitative changes of nuclear DNA were analyzed by microfluorometry in normal human epidermis during terminal differentiation. Normal human epidermis from five healthy volunteers was separated by an EDTA-trypsin method and fractionated by Percoll density gradient. Staining was carried out with either Feulgen reaction, Acridine Orange or 4'-6-diamidino-2-phenylindole (DAPI). When the cells with lower density (granular layer cells) were stained with Acridine Orange or DAPI, the greatest population was found at lower value of DNA than that in the cells stained with Feulgen reaction. After thermal denaturation procedure, a ratio of double-stranded DNA to single-stranded DNA was highest in the cells with lower density. These results seem to suggest the qualitative and quantitative changes of nuclear DNA during terminal differentiation of human epidermal keratinocytes.