Photomicrographs of Amyloidosis in a Mallard Duck

Photomicrographs from a Mallard Duck (Anas platyrhynchos) found dead in Missouri, U.S.A. (A) The glomerular mesangium (asterisk) is expanded by amorphous, eosinophilic, acellular material. H&E stain. (B) Tubules in medullary cones are often surrounded by amorphous, eosinophilic, acellular material. H&E stain. (C) Congo red positive light red to orange material (amyloid; arrows) expands the cortical interstitium. Congo red stain. (D) The glomerular mesangium is expanded by Congo red positive light red to orange material (amyloid; arrowheads). Congo red stain. (E) Low magnification of the kidney showing amyloid deposits with apple green birefringence under polarized light. Congo red stain. (F) Higher magnification of glomerulus showing amyloid deposits with apple green birefringence under polarized light (arrowheads). Congo red stain.