Introduction

Orange G / Aniline Blue reagent is a component of Mallory Trichrome kit used for treating the tested microscopic sample using three different stainings with differential counterstaining of two basic parts of the tissue (muscle and collagen fibers) in focus. Sample staining starts with Fuchsin Acid acidic dye that causes nuclei and muscles get stained red to pink. Phosphotungstic acid molecule then shuts out Fuchsin Acid dye molecules from collagen and thus enables Aniline Blue to bind, resulting in collagen being stained contrast blue in relation to previously used red dye. Orange G (molecule of the lowest molar mass) stains erythrocytes.