Peri-tangle neurites (Green arrows) are essential in the process of neuritic plaque formation. They are seen only in the neural tissue adjacent to post-necrotic neurofibrillary tangles and only in Alzheimer’s disease and in normal aging. Neuritic plaques and peri-tangle neurites are mutually interdependent (one does not occur without the other). It appears that a toxic material (presumably beta amyloid or a precursor) emanates from the dead nerve cell into the neural tissue causing degeneration in adjacent nerve fibers which either terminate on the dead cell or are passing by. This is one way, if not the only way, that beta amyloid (or its precusors) gain entrance into the neural tissue and this is likely a source of the extracellular deposit of insoluble beta amyloid in the neuritic plaques.
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