COMPARATIVE STUDIES ON AMOUNT OF DNA IN CELL NUCLEI OF MOUSE SKIN AFTER ADMINISTRATION OF CARCINOGENIC AND NON-CARCINOGENIC SUBSTANCES

The amount of DNA in cell nuclei was determined by microspectrophotometry on Feulgen‐stained preparations using basal cells from the back skin of mice after painting with 3‐methylcholanthrene (3‐MC), croton oil and turpentine, and from skin after a burn. In the hyperplastic epithelium of the skin painted with 3‐MC, the amount of DNA per cell nucleus was the same as that of normal skin but the mean amount of DNA in papilloma and atypical hyperplasia was slightly higher. However, no significant difference was found from that of the normal. In contrast to the above lesions, the amount of DNA in squamous cell carcinomas was elevated and the range of modal distribution was wider. In the hyperplastic epithelium induced by painting with croton oil or turpentine, the amount of DNA was also near the normal range. In the regenerating hyperplastic epithelium after a burn, the number of cells with an increased amount of DNA was higher for 2–5 days after the burn but no essential difference was observed from the normal. Copyright © 1968 Wiley‐Liss, Inc., A Wiley Company