Neuritic plaques in senile dementia of Alzheimer type: a Golgi analysis in the hippocampal region.

Tissue sections from the hippocampal region of patients with senile dementia of Alzheimer type were examined in 75-100 microns thick vibratome sections impregnated by the Golgi-Cox method and counterstained with cresyl violet. The morphology of dendrites and axons with neuritic plaques was frequently abnormal. Abnormalities included pleomorphic outpouchings of terminal and preterminal dendritic and axonal segments, many of which contained filiform processes occurring singly and in tufts. The axon collaterals of some hippocampal neurons appeared to branch richly as they entered plaques. Impregnated neurites could occasionally be traced from a neuritic plaque to adjacent pyramidal and local circuit neurons. The findings confirm that local neurons of different types contribute dendrites and axons to plaques and that these processes may proliferate within the confines of the plaques.