Abstract
Senile plaques, neurofibrillary tangles, and Pick bodies were examined by modified scanning electron microscopy from a low-power to an ultra high-power range. The amyloid core of the typical plaques was found to be composed of radially arranged rod-shaped components, which were made up of dense aggregation of meandering moniliform amyloid filaments about 15 nm in diameter. Bands with a mesh-like structure were observed outside the crown around the core. The compact plaques were nearly identical to the core alone of the typical plaques. The primitive plaques as a whole were analogous to the mesh-like structure around the typical plaques, and they both contained aggregates of filaments closely resembling amyloid fibers. In neurofibrillary tangles, the flamed shape stretched straight to the peripheries, the globosed shaped formed vortices, and only bundles of parallel filaments were observed. PHFs that constituted these structures were 25-30 nm in diameter, and many appeared constricted to a diameter of about 15 nm by rotating 180° to the left at a cycle of 70-80 nm. In Pick bodies, filaments were interwoven and formed a mesh-like structure, numerous granules were attached the filaments. Some filaments were large, being 20-30 nm in diameter, others were thin, being about 15 nm in diameter.
