DNA repair in thymocytes of mice undergoing thymic involution

DNA repair in mouse thymocytes before the onset of thymic involution was compared to that at successive stages during involution of the thymus. Repair of DNA in these cells after in vitro X-irradiation was evaluated by sedimentation of nucleoids in a sucrose gradient, as a measure of DNA supercoiling. DNA repair continued to function in the thymocytes even at ages when there was a dramatic reduction in the number of cells in the thymus.