Studies on replicating patterns of bovine sex chromosomes using 5–bromo-deoxyuridine (BrdU): I. The frequency of cell division and the length of cell cycle

Prior to the studies on the replicating patterns in bovine sex chromosomes, the frequency of cell division by the autoradiographic method of labeling with ³H-thymidine and the length of the cell cycle by the method of administration of 5–bro-modeoxyuridine (BrdU were examined in the cultured lymphocytes. The number of the cells labeled with ³H-thymidine increased punctually, and they almost attained their maximum number at 72 hours' labeling. In the cells to which BrdU had been added for over 36 hours, many cells passed through the cell cycle 3 times, and in the cells treated from 12 to 24 hours, almost all of the cells passed through the cell cycle two times. In the cells treated within 10 hours, almost none of the cells attained a full cell cycle. These results suggested that the length of the cell cycle in bovine cultured cells is about 12 hours .