Cell cycle peculiarities of the Ehrlich ascites tumour as revealed by cell counting and flow cytometry.

Based on own investigations general principles of cell cycle analysis by quantitative microscopic methods are discussed. Cell cycle peculiarities of the Ehrlich ascites tumour (EAT) are demonstrated. The numerical data yield information on the underlying type of growth expressed by the logistic function (Verhulst-Pearl). The effective tumour development starts with an exponential phase. In EAT the 5th day is regarded as representative for this stage. Then after a transition phase a steady state is reached. The 11th day after transplantation reflects best this phase of tumour development. By flow cytometric measurements DNA frequency distributions can be obtained in dependence of tumour age. The interpretation of the practically useful height of the second frequency peak in the histograms is discussed in relation to the underlying type of growth. The evaluation of the measurements reveals a characteristic change of the relative duration of the cell cycle phases G1, S, G2 and of the percentage of cells within these phases. Multiparameter single cell measurements complete the cytometric cell cycle analysis in relation to the position of cells in the cell cycle and allow a distinction between quiescent and proliferating cells. Finally the application of the parameters assayed on the biological model is extended to tumours in man.