<prompt> Which one of the following stain is specific for amyloidPASAlizarin redCongo redVon kossa  <response>: Ref Robbins 9e p257; Harrison 17e p2145 Amyloid is not a structurally homogeneous protein, although it always has the same morphologic appear- ance. In fact, more than 20 at last count, 23 different pro- teins can aggregate to form fibrils with the appearance of amyloid. Regardless of their derivation, all amyloid deposits are composed of nonbranching fibrils, 7.5 to 10 nm in diam- eter, each formed of b-sheet polypeptide chains that are wound together Fig. 4-31. The dye Congo red binds to these fibrils and produces a red-green dichroism birefrin- gence, which is commonly used to identify amyloid deposits in tissues. 