Sequence of Deposition of Amyloid in Strain A Mice and Relationship to Renal Disease2

Abstract

The sequence of spontaneous amyloid deposition in various organs and tissues, the time of appearance of related renal changes, and the general staining characteristics of the amyloid deposits at different ages were analyzed in 61 strain A/Sn male mice. The earliest deposits of amyloid were found in the alveolar septa of the lung in some animals 4 to 5 months of age. In mice 6 to 17 months old, the number of organs affected progressively increased and the frequency with which a given organ was affected increased. The incidence and localization of inflammatory processes and amyloid deposition were not correlated. In the kidney, amyloid was first observed interstitially near the tip of the papilla in animals 6 to 7 months old. Later, foci of necrosis were observed in the tips of some papillae in areas of amyloid deposition. This study confirms Dunn's observation that papillonephritis in strain A mice is associated with amyloidosis, and, further, demonstrates that amyloid deposition in the distal third of the renal papilla always precedes the papillary necrosis. Cortical changes subsequent to amyloid deposition in, and necrosis of, the renal papilla followed the histological patterns described by Dunn. The staining characteristics of the amyloid deposits were identical at all ages and consisted of a negative iodine reaction, strong metachromasia with crystal violet, a weak periodic acid-Schiff reaction, positive staining with thioflavine-T, weak Congo red staining, a positive alcian blue reaction, and a negative van Gieson's reaction.