Occurrence of diffuse amyloid deposits in the presubicular parvopyramidal layer in Alzheimer's disease.

Silver staining by a modified Bielschowsky's technique and immunostaining for beta-amyloid protein BAP have revealed the occurrence of diffuse amyloid deposits bilaterally in the presubiculum in each of fourteen Alzheimer's disease cases examined. Observations on serial blocks show these deposits to be localized in the parvopyramidal layer of the presubiculum proper and the transsubiculum. They are also observed in the cellular islands within the molecular layer of the subiculum but not in the parasubiculum. These amyloid deposits are not accompanied by neurofibrillary tangles, neuropil threads, or the aggregated microglial reaction which is characteristically associated with classic senile plaques. Convergence of input from limbic and cortical areas might play a significant role in the formation of these diffuse amyloid deposits.