Abstract
The use of the antibiotic drug mithramycin for cytoflurometric assessment of deoxyribonucleic acid in single cells has been studied in smears of a standard cell population of rat thymocytes. The optimal staining conditions have been determined including the influence of fixation (freeze-drying, formalin and ethanol). The drug equilibration time has been estimated in relation to the concentration of the mithramycin and to Mg++ was found to enhance the fluorescence intensity produced by the mithramycin-deoxyribonucleic acid interaction. The stability and the reproducibility of the fluorescence reaction are discussed.