In Luxol Fast Blue procedure for myelin, which differentiating agents are used?

• A. Lithium carbonate and 70% alcohol
• B. Hydrochloric acid and ethanol
• C. Sodium hydroxide and water
• D. Acetic acid and methanol

Answer: (A)

Differentiation after Luxol Fast Blue staining relies on a specific agent that selectively removes excess dye from nonmyelinated tissue while leaving myelin blue. The lysol blue binds strongly to myelin lipids, and treating with lithium carbonate in 70% ethanol clears background staining by dissolving extra dye from gray matter. This makes myelinated areas stand out clearly against the background, which is the whole point of the differentiation step. The lithium carbonate in alcohol combination is what gives that selective differentiation, so it’s the correct choice. Other differentiating approaches (like acid, base, or different solvents) aren’t the standard method for this stain and wouldn’t provide the same selective contrast.