In the course of Alzheimer's disease, specific CA1 pyramidal cells develop dendritic changes, which can only be observed transiently. Distal segments of the apical dendrite running through the stratum lacunosum-moleculare show spindle-shaped dilations filled with abnormal tau protein. The alteration eventually leads to amputation of the changed segment. The damage first appears at stage II in the evolution of the neurofibrillary changes [5], is best developed at stage III, and vanishes from the tissue at stage IV. It is usually not observed in stages V and VI (fully developed Alzheimer's disease).