Relationship of the development of radiation damage and repair on the regenerative activity of tissues of Rana temporaria tadpoles

Abstract

Rana temporaria tadpoles aged 20 days were exposed to 300 or 600 r of X-rays. The degrees of damage and recovery in the epithelium of the cornea, tail, and regenerating portion of the tail were studied, and differences were found which were related to the initial rate of cell division. The change of mitotic activity was used as a criterion of the extent of the injury and of the rate of the subsequent repair. The fall in mitotic index was more abrupt and pronounced in the cornea and epithelium where the rate of mitosis was relatively high. After radiation repair processes were more rapid in the tissues in which mitotic activity is normally high; nevertheless the recovery was incomplete. Regenerative activity was more distinctly shown after irradiation with a dose of 300 r; differences between the reactions of the various tissues to irradiation was less well shown with a dose of 600 r.