Mexican wolf, kidney, Congo red stain viewed under polarized light. The characteristic amyloid fibrils could not be appreciated because of formalin fixation artifacts. Mexican wolf, kidney, electron micrograph, uranyl acetate and lead citrate stain. The glomerular basement membrane is thickened by amyloid deposition. Mexican wolf, kidney, electron micrograph, uranyl acetate and lead citrate stain.
Increased magnification shows the granular to fibrillar appearance of amyloid.
Systemic amyloidosis can be classified as primary, secondary, or familial. Secondary amyloidosis is observed most commonly in animals and has been described as a reaction to diverse inflammatory stimuli. Secondary amyloid deposits usually are sensitive to potassium permanganate digestion. Primary amyloidosis is less frequently observed. In this condition, the deposition of amyloid is the result of plasma cell dyscrasia, including both lymphoid and plasma cell neoplasms.