n :  an abnormality of the cytoplasm of the pyramidal cells of the hippocampus and neurons of the cerebral cortex that occurs esp. in Alzheimer's disease and appears under the light microscope after impregnation and staining with silver as arrays of parallel thick coarse argyrophilic fibers .
 
 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2004.