Studies in fluorescence histochemistry: I. The demonstration of sulphomucins*

Abstract

SYNOPSISSulphated mucosubstances in sections of coagulant‐fixed tissue emit a variable yellow to red fluorescence after being stained with purified coriphosphine at pH 2 to 4. Unfortunately this fluorescence is sometimes indistinguishable from a similarly coloured fluorescence emitted by nuclei, oxidized sulphoproteins and some sialo‐mucins, which, however, can be eliminated more or less selectively either by (1) a preliminary Feulgen hydrolysis and condensation with N,N‐dimethyl‐m‐phenylene diamine; or (2) by pretreatment with a solution of ferric alum; or (3) by a previous methylation with methanolic thionyl chloride, followed by reduction with lithium aluminium hydride in hot dioxane and then by saponification (a sequence of reactions which, in theory but not always in practice, should remove all polyanionic groups in the tissue except sulphate groups on sulphated mucopolysaccharides); or (4), best of all, by staining sections in a very dilute solution of thiazol yellow at pH 2 after they have been stained in coriphosphine.The rationale and limitations of these methods are discussed critically.