Under polarised light, the congo red stained amyloid shows-
(A) Pink or red color (B) White color (C) Apple green birefringence (D) None
(C) Answer- C. Apple green birefringenceAmyloid has an affinity for Congo red stain; therefore this method is used for confirmation of amyloid of all types. If the stained section is viewed in polarised light, the amyloid characteristically shows apple-green birefringence due to cross- b-pleated sheet configuration of amyloid fibrils.The stain can also be used to distinguish between AL and AA amyloid (primary and secondary amyloid respectively).