Histopathological study of amyloidosis occurred in white Pekin ducks.

Abstract

In the present study, we investigated spontaneous amyloidosis occurred in white Pekin ducks to clarify the type of deposit fibrils and the mechanisms of fibril formation. Amyloid protein of ducks was sensitive to oxidation with potassium permanganate and completely lost the affinity to Congo red. Immunohistochemically the proteins cross-reacted to the rabbit anti-human amyloid AA antibody. So it was concluded that amyloidsis of ducks was secondary type and the major component of amyloid was amyloid AA protein. The precursor substance of AA protein of ducks was produced by hepatocytes, in similar fashion to human or rodents. With regard to pathogenesis, ducks amyloidosis was influenced by preceding inflammation, because numerous cases of amyloid ducks showed various inflamed alterations in the sole of the foot zone. In lightand electron microscopically, morphological deposition pattern of the fibrils showed a typical AA form. The fibrils were observed on the walls of blood vessels and the neighboring connective tissues. However, we could find a characteristic finding that amyloid fibrils were mainly formed in the cytoplasm of reticuloendothelial system cells, especially in the histiocytes. Subsequently, intracytoplasmic fibrils were transformed into a amyloid nodule and the nodules were also fused into a large homogeneous mass.