Cytofluorometric study of nuclear DNA in experimentally induced epidermal hyperplasia.

The rate of cell proliferation in the basal cell layer by epidermal hyperplasia of guinea pig ear was investigated with cytofluorometric method. Epidermal hyperplasia was caused by tape stripping or the application of n-hexadecane or retinoic acid. In non-treated epidermis, the mean of the relative numbers of cell in each phase to the total cell number was 62.8% (G1), 34.6% (S) and 2.6% (G2 + M), respectively. In the case of tape stripping, growth in the relative number of S phase cells showed approximately the same proportions at 3 to 12 h. At 24 h, the relative number of S phase cells was lower than that in non-treated epidermis. By the application of n-hexadecane, the relative number of S phase cells was highest at 6 h. It was highest at 3 h by the retinoic acid application. On the other hand, the value of nuclear protein in G1 cells was highest at 6 h by both tape stripping and n-hexadecane application, while the value by retinoic acid was similar to that in non-treated epidermis.