[Qualitative approach of DNA content analysis by flow cytometry]

One step DNA staining procedures are very easy to use. Reduced staining time and small amount of needed components explain the world wide use of these protocols. The heterogeneity of the results obtained with these technics during a study of different mice organs has let the authors to think that there was a close relationship between this heterogeneity and DNA staining technics. The authors have observed the same discordances with some human tissues (parathyroid, prostatic adenoma...). They disappear when the same cells are stained with a procedure that associates to propidium iodide and RNAse a pretreatment of nuclei by trypsin and spermin. These molecules are DNA stabilizing components. So one can develop the hypothesis that the abnormalities observed with the one step procedures are due to a decondensated state of DNA that allows the fixation of a higher amount of stain. The main point will be to find a direct relationship with different physiological or pathological states. Now, it is necessary to sensibilise users against the risk of false abnormal DNA content detection through the one step procedures.