SENSITIVITY OF SKIN OF HAIRLESS MICE TO CHEMICAL CARCINOGENESIS

Abstract

The sensitivity of hairless mice to cutaneous chemical carcinogenesis was compared with that of normal mice of the same strain with hair. A single application of 125 .mu.g methylcholanthrene in benzene was given to 48 hairless male mice (hr/hr Oslo strain) and to 96 male mice of the same strain with hair. Among hairless mice, there were 94% papilloma-bearing animals with a total of 5.9 tumors/animal after 18 mo. of observation, compared to 22% papilloma-bearing animals with an average of 0.3 tumors/animal among the mice with hair. The hairless mice included 31% carcinoma-bearing and 23% sarcoma-bearing animals but only 1% of the mice with hair were carcinoma bearing and 3% were sarcoma bearing. Hairless mice of the hr/hr Oslo strain were not refractory to chemical carcinogenesis, but under the experimental conditions used in this study they were significantly more sensitive than were mice from the same strain with hair. Giovanella reported almost opposite results in 1970 and came to the general conclusion that hairless mice were refractory to chemical carcinogenesis due to lack of hair follicles. Since hairless mice always have some hair follicles and rudimentary pilosebaceous appendages, comparisons between chemical carcinogenesis in hairless mice and mice with hair can neither strengthen nor weaken any theory about the hair follicle origin of epidermoid carcinomas of mouse skin.