Ultrastructure of perivascular amyloid fibrils in Alzheimer's disease.

Perivascular amyloid fibrils in the brains of patients with Alzheimer's disease have been examined by electron microscopy. The amyloid fibrils showed a hollow rod structure and consisted of globular substances. Each turn appeared to be composed of five globular subunits. These findings coincide with the ultrastructure of amyloid fibrils obtained from replicas made by a rapid freezing method.