Which dye is used for demonstration of amyloid in tissue sections?

• A. Thioflavin T
• B. Thionine
• C. Toluidine blue
• D. Acridine orange

Answer: (A)

Thioflavin T is used to demonstrate amyloid in tissue sections because it binds specifically to the cross-β-pleated sheet structure of amyloid fibrils. When bound, it becomes highly fluorescent, emitting bright yellow‑green light under UV or blue light, which makes even small deposits visible with fluorescence microscopy. This property provides a quick and effective way to visualize amyloid in paraffin or frozen sections. The other stains listed serve general histology or nucleic acid staining and do not selectively highlight amyloid results the way Thioflavin T does.