Alzheimer's disease: beta-amyloid precursor protein expression in plaques varies among cytoarchitectonic areas of the medial temporal lobe.

The anatomic distributions of beta-amyloid peptide (beta AP) and beta-amyloid precursor protein (beta APP) in the medial temporal lobe were examined with immunocytochemistry in Alzheimer's disease. beta AP-containing plaques were found most frequently in the cortical and basal regions of the amygdala, and in the hippocampal CA1, subiculum, and dentate molecular layer. beta APP expression in plaques was found in a similar distribution, with some, but not all beta AP plaques also showing beta APP. In the cortical and basal amygdala, some cases showed beta APP in the centers of plaques, whereas in the hippocampus, all cases displayed beta APP mainly in plaque neurites. The lateral regions of the amygdala contained mainly diffuse beta AP plaques which had little beta APP. These findings suggest that although beta APP expression and beta AP deposition generally colocalize, processing of beta APP may vary among closely interconnected anatomic regions.