Which fixative is commonly used for preserving tissue for Luxol fast blue staining?

• A. Neutral buffered formalin
• B. Acetone
• C. Acetic acid
• D. Osmium tetroxide

Answer: (A)

Luxol fast blue targets myelin lipids, so the fixative chosen should preserve tissue architecture without extracting those lipids. Neutral buffered formalin fixates by cross-linking proteins, which preserves morphology while largely keeping lipids available for the dye to bind during the Luxol fast blue protocol. This makes subsequent differentiation steps reliable and consistent.

Other options either act as solvents or heavy fixatives that can alter lipid content or require special handling. Acetone is a lipid solvent and can remove lipids, compromising the stain. Acetic acid is acidic and can affect staining patterns. Osmium tetroxide is a lipid fixative used mainly for electron microscopy and is not standard for routine Luxol staining.