The use of the digital cell image analysis of Feulgen-stained nuclei to detect apoptosis

Cell death is an essential event in the functioning of multicellular organisms. It plays a role opposite to that of mitosis in the regulation of cell populations. In the present work, we describe an original methodology which permits the easy detection and count of apoptotic cells in a given tissue. This methodology is based on the digital cell image analysis of Feulgen-stained nuclei, which also permits the calculation of the proliferation index, i.e. the percentage of cells in the S phase of the cell cycle. This percentage of cells in the S phase is strongly related to the mitotic index. Our methodology, which involves the multivariate analysis of 14 morphonuclear parameters computed by means of the digitized cell image analysis of Feulgen-stained nuclei, was applied here to a well-known biological apoptosis model, namely glucocorticoid-treated rat thymocytes. The parameters that permitted the detection of apoptotic cells were the integrated optical density, a parameter that describes the nuclear DNA content, and the run length percentage and long run length parameters which are related to the pattern of chromatin condensation. This determination can be carried out on a relatively small number of cells.