A working solution of 0.5 % of thioflavin T in 0.1 N HCl (mixed well and filtered before use, aliquoted, and stored frozen as needed) is used. The sections are deparaffinized and rehydrated. Using a hydrophobic marker, the specimen section and an adjacent positive control section are encircled on the top of the slides. A drop of the working solution of thioflavin T is placed on the slides, which are subsequently kept in a humidity chamber for 15 min. The slides are rinsed in deionized water (for 5 min) and kept in deionized water while coverslipping with Aquamount. The frozen sections are rinsed two times in PBS (for 10 min each) prior to incubation with thioflavin T and, thereafter, rinsed sequentially in PBS and deionized water (for 5 min each) and coverslipped. Thioflavin stain is viewed under a fluorescein gate using a standard immunofluorescence microscope. Thioflavin T fluoresces only when bound to amyloid fibrils, where it shows a bright yellow-green fluorescence. In contrast, in the absence of amyloid deposits, the dye fluoresces faintly.