[Selective demonstration of amyloid deposits and methodical possibilities of analysis of their ultrastructural differences (author's transl)].

In preparations stained with congo-rot and covered with arabic gum amyloid deposits reveal intensive, positive birefringence. Collagen is isotropic or shows a mild negative birefringence. This method is most suitable for selective optical demonstration of amyloid deposits. On the base of investigations on ultrastructural stability of amyloid deposits (resistance to performic acid and induced proteolysis) two types may be distinguished: (1) amyloid deposits of labile structure (generalized, secondary amyloidosis) and (2) amyloid deposits of stable structure (generalized primary amyloidosis, local and senile amyloid deposits).