UV-induced squamous cell carcinomas in the hairless mouse. Morphological characteristics and transplantation in the syngenic and nude mouse.

Squamous cell carcinomas were induced by UVB in the hairless mouse HRO hr/hr. Twelve mice were irradiated three times a week at a dose of 0.19 J/cm2. The average latency period for the appearance of the first tumour is 16 weeks and by the 21st week, tumour incidence is 100%. Further observation of these tumours shows that their growth is independent of irradiation dose and that the tumours continue to appear even after cessation of irradiation. Histological and cytological examination of these tumours show them to have characteristics of malignancy. Transplantation in athymic mice suggests that UVB provokes immune deficiencies in hairless mice similar to those seen in conditioned nude mice.