Abstract
In an attempt to elucidate the nature of ruthenium red reactions of substances in histochemical specimens, the effects of added electrolytes upon the reactions of model polyanions on filter paper and in tissue have been studied according to the Scott-Dorling type of critical electrolyte concentration (CEC) principle. The results obtained in the present experiments indicate that any of the three anionic groups, sulfates, phosphates and carboxyls can be responsible for the ruthenium red reactions of polyanions and that the dye binds to polyanions largely forming a salt type of linkage. However, ruthenium red is not a dye of choice for use in stainings based upon the CEC principle, inasmuch as certain moieties of the dye cations appear to interact with cationic electrolytes.
