Fluorescent Staining of Amyloid-Beta Plaques

Tissue sections prepared on microscope slides were deparaffinized, rehydrated, and immersed in a solution of 0.002% (w/v) thioflavin S (Sigma-Aldrich, St. Louis, MO, USA) and 50% ethanol. Following sequential rinsing with 50% ethanol and PBS, nuclei were counterstained with 4′,6-diamidino-2-phenylindole dihydrochloride (DAPI). The sections were mounted using a commercially available mounting medium (Dako Denmark A/S, Glostrup, Denmark). The thioflavin S–labeled Aβ plaques and DAPI-stained nuclei were observed under a fluorescence microscope (Eclipse 80i, Nikon, Tokyo, Japan) at 100× magnification.