Reference method for the detection of protein deposits in renal biopsy.

 

It is a nuclear stain obtained with ferric hematoxylin and is associated with cytoplasmic staining with orange G and highly elective collagen staining with aniline blue.

 

The electivity of the method is based on the different degrees of chemical affinity of the dyes used for tissue macromolecules. The role of phosphomolybdic acid, in particular, is fundamental because it serves as a bridge between the tissue structures to which it selectively binds (collagen fibrils, cell membranes, etc.) and aniline blue (amphoteric dye). The other component of the AFOG mixture, the orange G, having no affinity for phosphomolybdic acid, stains the remaining structures (which did not form any bond with phosphomolybdic acid). Orange G (OG 6), an acidic dye that reacts with mature squamous cells due to its affinity for keratin. Acid fuchsin stains bright red potential protein deposits.