Cytological sub-division of S-phase in the Syrian hamster (Mesocricetus auratus).

Using BrdU/Hoechst 33258/Giemsa methods for detecting replicating chromosome bands, a method is described by which the DNA synthesis phase may be sub-divided on the basis of distinctive patterns displayed by certain chromosomes.--Applied to asynchronous populations successively sampled through one cell cycle, cells in S can be "unscrambled" and replaced in their correct time sequence.--This helps to overcome the sampling-time variable inherent in such populations, and allows a clearer picture of the progression of events both qualitatively and quantitatively.