STRIATION IS THE CHARACTERISTIC NEURITIC ABNORMALITY IN ALZHEIMER-DISEASE

In this study, we found that neuropil threads of Alzheimer disease, ra ther than being continuous filaments along cell processes, show multip le interruptions. They are segmental in nature and therefore appear as striations rather than continuous filaments along the length of the n eurite. Neuritic striation is not an artifact of section thickness sin ce the majority of abnormal filament accumulations are extremely short . The dominance of short striations demonstrates that argyrophilic gra ins, rather than being distinct structures, simply represent a short v ariant of striation and that longer striations are arbitrarily conside red neuropil threads. Ultrastructural examination showed that the inte rvals between striations lack a cytoskeleton. We suggest that neuritic striations may interrupt the microtubule system functionally blocking fast neuritic transport as well as playing a role in loss of neuronal connectivity. (C) 1998 Elsevier Science B.V. All rights reserved.