Multiparameter geometric and densitometric analysis of the G0-G1 transition of WI-38 cells.

Automated image analyses were performed using Feulgen stained smears of WI-38 cells that were either confluent, or that had received a nutritional stimulus to proliferate 3 hr before collection. These experiments show that it is possible to observe changes in morphometric and densitometric parameters of nuclei that correlate with structural and functional differences in isolated chromatins from quiescent G0 and proliferation G1 cells that have been demonstrated by other means. Scatter plot analyses of the data indicated the presence of nuclear images from the stimulated G1 population that had the same deoxyribonucleic acid content as the confluent G0 cells, but had greater areas, perimeters and horizontal projections and smaller mean free paths, form factors, and average optical densities. Multiparameter cluster analysis permits, even minimally, an objective, model-independent identification of G0 from G1 cells that present an increased nuclear dispersion (i.e., lower average optical density) systematically accompanied by increased nuclear convolution (i.e., lower form factor), both compatible with the reported increase in available binding sites with respect to G0 cells.