Gray matter is practically colorless in a correctly performed Luxol fast blue stain.

• A. True
• B. False
• C. Only in gray matter
• D. It stains gray matter blue

Answer: (A)

Luxol fast blue targets myelin lipids, staining myelinated white matter blue. Gray matter has much less myelin, so it does not take up the blue dye and remains essentially colorless after the stain (with a counterstain used only to visualize the cell bodies). In a correctly performed protocol, the blue color marks white matter while gray matter stays colorless unless the counterstain is considered, making the statement true.