Used primarily in histology to stain acidic polysaccharides such as glycosaminoglycans (GAGs) in cartilage tissue. It binds to negatively charged sulfate and carboxyl groups, making it ideal for visualizing cartilage matrix in tissue sections. Commonly applied in studies of skeletal development, cartilage degeneration, and extracellular matrix composition. Often used in combination with other stains like nuclear fast red or safranin O for contrast. Also useful in detecting mucins in epithelial tissues and identifying acid mucopolysaccharides in pathological samples.