Sudan Black B is widely used as a biological stain in histology and cytology to detect lipids in tissues and cells. It is particularly effective in staining phospholipids, lipoproteins, and neutral fats, making it a valuable tool in identifying lipid-rich structures such as myelin sheaths in nerve tissues. In microbiology, it is employed to stain lipid-containing granules in bacteria, aiding in the differentiation of certain species. Additionally, Sudan Black B is used in hematology to stain lipid-rich granules in leukocytes, helping to diagnose disorders like leukemia. Its ability to bind to lipids also makes it useful in research studies focused on lipid metabolism and storage diseases.