Histology, cytology and other related scientific disciplines study the microscopic anatomy of tissues and cells. In order to achieve a good tissue and cellular structure, the samples need to be stained in a correct manner. Methylene Blue powder dye is used in various staining methods in microscopy. It is used for preparation of Romanowsky polychromatic methylene blue and as a part of polychromatic dye for staining bone marrow, animal and herbal material. Methylene Blue is a primary dye for staining acid-fast bacteria acc. to the Ziehl-Neelsen method that uses the Loeffler Methylene Blue reagent.