Azure A chloride is widely used in biological staining and histology. It is particularly effective as a metachromatic dye, allowing for the differentiation of tissues and cellular components under microscopic examination. In microbiology, it aids in the identification of specific cell structures, such as mast cells and mucopolysaccharides. Additionally, it is employed in research for studying nucleic acids and chromosomes, providing clear visualization of genetic material. Its staining properties make it valuable in diagnostic laboratories for analyzing tissue samples and detecting abnormalities.