ABSTRACT
Amyloidosis is defined as deposits that bind the cotton dye Congo red and demonstrate green birefringence when viewed under polarized light. Deposits of amyloid are always seen extracellularly, and are amorphous under the light microscope. With standard hematoxylin and eosin stains, the deposits appear pink. When viewed under the electron microscope, amyloid deposits appear as rigid, non-branching fibrils of indefinite length and a width of 9.5 nm. Amyloid fibrils are insoluble but form a suspension in distilled water. Repeated homogenization with saline of tissues containing amyloid, followed by suspension in water, forms the basis for the purification of amyloid.1
