Red-blue staining of hydrolysed nucleic acids in paraffin sections

Abstract

A previous treatment with 10% HC1 in tetrahydrofuran for 2-3 min at 37° C hydrolyses DNA while substantially preserving RNA in formol-fixed paraffin sections. If this treatment is followed by dyeing with basic fuchsin-thiazine or oxazine mixtures, the basic fuchsin stains DNA, the blue dye cytoplasmic RNA, though nucleolar RNA is not well preserved. A specimen sequence is to treat the hydrolysed section with a mixture of 1% aqueous trimethylthionin (Chroma), 15 ml; 0.1% basic fuchsin (G. T. Gurr), 4 ml; and glacial acetic acid, 1 ml. Stain for 15-30 min, dehydrate in acetone, then pass sections through xylene to polystyrene. The specificity of this stain for cytoplasmic RNA is sharper than that of methyl green-pyronin; hence the technic given can be a useful addition to the standard Unna-Pappenheim procedure.