Immunoelectron microscopic localization of amyloid beta protein in the diffuse plaques of Alzheimer-type dementia.

We examined the ultrastructural localization of beta protein in diffuse plaques of Alzheimer brain by indirect immunoperoxidase technique. Intense immunoreaction products, scattered sporadically in the diffuse plaques, were located on small bundles of several amyloid fibrils and/or amorphous materials between amyloid-related cell processes (ARCP). Deposits of beta protein were also seen on parts of the cell membrane of ARCP, suggesting the importance of ARCP in plaque amyloid deposits.