Aniline blue diammonium is a commonly used component in polychromatic staining agents. It is employed in staining collagen fibers in tissue sections, particularly with the Masson's trichrome staining method, which imparts a blue color to collagen. Additionally, this dye is suitable for the selective staining of callose in plant specimens and for histone staining to assess nuclear maturity. Aniline blue diammonium is also utilized in Gomori's one-step trichrome stain and Mallory's connective tissue stain, making it suitable for tissues such as the kidney and intestines.