Electron microscopist’s view of the Alzheimer’s plaque

Alzheimer’s disease (AD) is characterized by extracellular aggregation and deposition of Amyloid-beta peptide in the form of diffuse and fibrillar plaques. More than 50 years ago electron microscopic studies in humans have characterized the structure of the amyloid plaque and neurofibrillary tangles. More recently animal models of AD-type amyloidosis have provided excellent opportunities to study plaque structure during the development and expression of AD-type pathology. Ultrastructural data from a variety of transgenic mice overexpressing mutant amyloid precursor proteins, mutant presenilins, with or without human ApoE knock-in isoforms, are highly comparable to classical electron microscopic findings in AD. This review is an attempt to evaluate, from an electron microscopist’s point of view, the structural identity of AD type pathology, and the mature amyloid plaque in particular.