RESUMEN
The staining procedure using the monoclonal antibody to BrdUrd involved the following important steps: the duration of BrdUrd labeling time, the concentration of HC1, the duration of HCI treatment for cellular DNA partial denaturation and so on. The ratio of mean intensities between BrdUrd positive cells and BrdUrd negative cells, the proportion of cell aggregation occuring during HCI treatment, the relative fluorescence intensity and coefficient of variation (CV) of G_1 peak were considered as the criteria of optimal conditions of the whole staining procedure. The optimal results of this staining procedure were obtained under the conditions of 30 rain BrdUrd labeling time, 2.4 mol/L HC1, 30 min HC1 treatment, 1 hour incubation of the monoclonal antibody to BrdUrd and without RNase treatment. With this staining procedure, the optimal staining results were obtained for KF-1, KFr, HeLa and IK-90 cell lines.