Radiation effect on recovery of the freezing-induced ulcer in the mouse skin

X-ray irradiation of 1,000 R or 3,000 R to the freezing-induced ulcer caused no change in ulcer healing speed. With irradiation to the surrounding area of the ulcer, 1,000 R irradiation induced no delay in reduction of the ulcer, whereas 3,000 R irradiation delayed the healing of the ulcer. Cellular density and 3H-thymidine labeling index in the surrounding area were both higher in the 3,000 R-irradiated group than in non-irradiated group. In the 3,000 R-irradiated group, healing of the ulcer was delayed in spite of increased proliferation of the cells. This suggested, coupled with the presence of disarrangement of the basal cells, irregular size of the nuclei, enlarged nuclei, megakaryocytes, and thickened layers, that rapid differentiation and movement of the cells were disturbed. (Ueda, J.)