Senile plaques are located between apical dendritic clusters

The location of senile plaques (SP) in human cortex has been studied in relation to the dendritic architecture of the neocortex. Senile plaques were examined in patients with normal senescence and with Alzheimer's disease. The study utilizes a monoclonal antibody to microtubule-associated protein 2 for selective immunocytochemical visualization of dendrites and thioflavin S to visualize SP. The immunocytochemical analysis demonstrated the fascicular organization of pyramidal cell apical dendrites. Senile plaques were located between dendritic clusters with pyramidal cell apical dendritic shafts excluded from plaques. The close correlation between plaque diameter and interfascicular distances suggests that the boundaries of the vertically organized bundles may be an architectural constraint on plaque size.