Morphological study of amyloid fibrils and preamyloid deposits in the brain with Alzheimer's disease.

In addition to the ultrastructural study of amyloid fibrils, amyloid fibrils and preamyloid in the brain which had the fine ultrastructure of a well-preserved neuropil were examined using methenamine silver stain by light and electron microscope. In serial sections, amyloid fibrils in extracellular spaces continued directly to the capillaries. Using methenamine silver stain, silver granules were deposited at the amyloid fibrils and in extracellular spaces forming diffuse plaques. Many silver granules in the extracellular spaces seemed to strain preamyloid surrounding the capillaries. These findings to indicate that the capillaries have an important role in the formation of amyloid fibrils at least in some senile plaques.