Which one of the following stains is specific forAmyloid?
Periodic Acid schif (PAS)
Alzerian red
Congo red
Von - Kossa
Ans. is 'c' i.e., Congo Red "To differentiate amyloid from other hyaline deposits (eg. Collagen and fibrin), a variety of histochemical techniques are used, of which the most widely used is Congo Red" - Robbins 7'/e p. 259 Staining for Amyloid Congo red : It is the most widely used specific stain for amyloid. Iodine staining : It is used for unfixed specimen or histological section. Amyloid stains mahogany brown and if sulfuric acid is added, it turns violet. Thioflavin 'T' and `S' give secondary immunoflurescence with ultraviolet light. Thioflavin T is more useful for demonstrating juxtalomerular apparatus of the kidney. Metachromatic stains like crystal violet and methyl violet give rose pink appearance. Amyloid is PAS positive.