Studies on synchronous division of tissue culture cells initiated by excess thymidine

Abstract

Summary Treatment of a cell line derived from a human kidney with excess thymidine caused a blocking of DNA synthesis, which resulted in a synchronization of the cell cycle after removal of thymidine. At 1 ½ and 3 hr post-washing 80–90 per cent of the cells were in S phase. The mitotic peak was found 8–10 hr post-washing. At that time 15–25 per cent of the cells were in mitosis and at least 60 per cent of the cells divided between 6 and 12 hr. No damage due to thymidine treatment was revealed by microscopic observation and cloning experiments.