THE APPLICATION OF AGE DISTRIBUTION THEORY IN THE ANALYSIS OF CYTOFLUORIMETRIC DNA HISTOGRAM DATA

Abstract

Age distribution theory was employed in a model to analyze a variety of histograms of the DNA content of single cells in samples from mouse sarcoma, mammary tumor and EL4 leukemia growing in tissue culture. The method produced satisfactory correspondence with the experimental data in which there was a wide variation in the proportions of cells in the intermitotic phases, and good agreement between the 3H-thymidine labeling index and the computed index and the computed proportion in the S phase. The model has the capacity to analyze data from populations which contain a proportion of noncycling cells. Reliable results for the growth fraction and also the relative durations of the intermitotic phase times cannot be obtained for the data reported here from DNA histograms alone. To obtain reliable estimates of the growth fraction the relative durations of the phase times must be known, and conversely, reliable estimates of the relative phase durations can only be obtained if the growth fraction is known.