[Impulse cytophotometric investigations on tumour material (author's transl)]

By impulse cytophotometry (ICP) we can get the distribution of the frequency of cell nuclei as a function of the fluorescence intensity. The interpretation of the curves is only possible on the basis of histophysical and histochemical features. The following problems are discussed: specificity of staining with ethidium bromide, pretreatment, detritus, comparison with other independent methods. The second peak of the karyogram consists of G2-cells and, in polyploidy of tetraploid cells. This peak is often high in cell suspensions of malignant tumours; sometimes we found polyploidy up to 16c. The stem line concept is discussed. The ICP is a valuable aid in exfoliative cytology, but no screening method.