ALTERNATIVE STAINING METHODS FOR LOWICRYL SECTIONS

A number of stains and stain combinations have been identified that, when used with the hydrophilic resin Lowicryl K11M, produced marked improvements over aqueous uranyl and lead salts (UA-Pb) in terms of low granularity, specificity, and range of components contrasted. Three test specimens, tobacco mosaic virus (TMV), starfish sperm, and cultured mouse fibroblasts, were used to evaluate stain characteristics. UA-Pb showed a preference for nucleic acids, which were stained specifically by osmium ammine-B at pH 1.5. A number of stain combinations in which UA was followed or preceded by salts containing barium, manganese, tungsten, molybdenum, and vanadium provided excellent staining of protein-containing components, each stain combination being unique in terms of the degree to which specific components were discriminated. These stains were particularly effective for visualizing internal components of the nucleus where a number of fibrillar and particulate structures not seen with UA-Pb were well constrasted.