Cytochemical differentiation of nucleic acids with a Schiff-methylene blue sequence

A method is described whereby a Feulgen type of hydrolysis of deoxyribonucleic acid is carried out on paraffin sections of routinely fixed tissues by controlled exposure of the sections to Bouin's fluid. Subsequent staining with Schiff reagent followed by methylene blue distinguishes red-to purple-stained deoxyribonucleic acid from blue-stained ribonucleic acid. This Schiff-methylene blue sequence visualizes ribonucleic acid in nucleoli and the chromidial substance of various normal and neoplastic cells and provides an assessment of their protein synthetic activity. The method has proved valuable in demonstrating normal immunocytes and immunoglobulin-forming tumor cells in pathologic specimens.