Image of a classical neuritic plaque, as it occurs in large number in Alzheimer disease. Centrally located is a round dense core of amyloid; the borders of the core are ragged (black core). Around the centrally located core is a loose-textured halo in which are scattered dystrophic neurites (black rods, dots, which are small; however, of variable sizes). At the periphery of this pale halo, the gray mottled area is made up of amyloid deposits, which are much less dense than within the black centrally located core mentioned above. Within this peripheral zone of relative low-density amyloid are intermingled, rare, dystrophic neurites, and astrocytic processes, and microgliocytes, which appear as dark oval or round spots or filamentous debris.
Dr. Jean-Paul Vonsattel, Professor of Pathology, Director of the Taub Institute-New York Brain Bank, Columbia University Medical Center