[Structure and repair of rat thymus DNA during long-term irradiation].

During long-term fractionated irradiation (0.5 Gy, daily) the molecular weight of single-stranded DNA of the thymus of exposed rats remained the same as that of intact animals till the dose of 25 Gy had been cumulated. The integrity of the DNA structure was ensured by the repair of DNA and elimination of cells with unrepaired lesions. The role of repair decreased and the elimination of cells increased with increasing cumulative dose.