A new principle in polychrome staining: a system of automated staining, complementary to hematoxylin and eosin, and usable as a research tool.

A staining system is described in which each stage forms a separate module or unit. All reagents, concentrations of dye, ratios of phosphotungstic acid to dye, pH values, temperature and staining times are standardized and only aqueous solutions used. The technic uses equal strength solutions of orange G, acid fuchsin and methyl (or aniline) blue, in ascending order of molecular size, at pH 2.5 (range: 2.3 to 2.7). Phosphotungstic acid is incorporated in the dyebaths, not used separately, and the combination of this with ferric alum hematoxylin (Lillie's by preference) and either naphthol yellow S or picric acid as a primer, enables fibrin and cytoplasmic components to be demonstrated vividly, with other tissues shown in clear contrasting colors. Erythrocytes are yellow, fibrin red and collagen blue. The system permits substitution of dyes, lending itself to both manual and computer recording and analysis, helped by a notation system for identifying variants. Many of the factors are variable at will. The system aids research into the mechanism of polychrome staining, and, by extrapolation, into the mechanism of action of other stains. Two manually or machine usable progressive polychrome technics intended for routine use are described. They identify tissue components consistently, complementing the standard hematoxylin and eosin stain, and deserve equal attention during reporting. Variants may be used for one-minute one-stage staining of frozen sections, or to give strong colors with 2 millimicrons acrylic sections.