Widely used in histology and cytology as a staining agent, particularly in combination with other dyes for demonstrating acidic polysaccharides in tissues. It is a key component in the preparation of Romanowsky-type stains, which are essential for blood smear analysis, enabling clear differentiation of white blood cell types. Also utilized in microbiology for staining bacterial capsules and in some cases for fungal detection. Its metachromatic properties allow visualization of glycosaminoglycans in connective tissues, making it valuable in diagnosing certain pathological conditions involving mucopolysaccharide accumulation.