Histochemical similarity of senile plaque amyloid to apudamyloid.

Senile plaque amyloid of both isolated and perivascular (dyshoric) types was compared histochemically to other major types of amyloid. In contrast to most amyloids tested, senile plaque amyloid contained less tryptophan and tyrosine reactivity and more alcianophilia. These histochemical features indicate that senile plaque amyloid is similar to apudamyloid, and suggest that local factors are more important than systemic circulating factors in its genesis. The implications of these histochemical observations are discussed.