We used intracellular injections of Lucifer yellow (LY) in fixed brain tissue from AD patients to visualize and reconstruct dendritic arbors of pyramidal neurons—using high-resolution tile scan stacks of confocal microscopy images—to compare neurons that were free of signs of any neurofibrillary pathology with those showing either diffuse phospho-tau (putative pre-tangle state) or aggregated tau NFT. Here, MAPT is linked to Alzheimer disease.