Further Autoradiographic Studies of the Lens Epithelium: Normal and X-Irradiated Rat Eyes

Introduction The effect of roentgen irradiation on deoxyribonucleic acid (DNA) synthesis in the epithelium of the rat lens has been investigated recently using autoradiography after intraperitoneal administration of H 3 -thymidine. 1 This study demonstrates that the mitotic inhibition resulting from a dose of 1,000 r x-rays is accompanied by a temporary depression in the number of cells undergoing DNA synthesis. The latter effect appeared to be due mainly to a presynthetic block which prevented new cells from entering the synthesizing (S) period. The results indicated further that the synthetic process is briefly interrupted in some of the cells which were in the S period at the time of irradiation; although, generally, DNA duplication was completed despite irradiation. The aim of the present experiment was to determine the fate of cells irradiated during the synthesizing period. For this purpose, rats of the same strain and age as those previously used