Alzheimer's Disease; neurofibrillary tangles and neuritic plaques: This slide from a silver impregnated section of the hippocampus from a severely demented patient shows numerous neuritic plaques and neurons containing neurofibrillary tangles. The neurofibrillary tangles are intraneuronal, while the neuritic plaques are large extracellular collections of abnormal nerve cell processes, degenerating synaptic terminals, glia and amyloid.