Fig. 1.
Amyloid plaque load and APP expression in hippocampus of 18-month-old Wt and Tg mice. Tissue was immersion fixed, sectioned at 6 μm, and counter-stained with hematoxylin. A and B show amyloid plaques labeled with anti-human β amyloid (6F3D). No plaques are present in Wt animals (A) and can be seen localized to the subiculum, stratum oriens, and stratum moleculare of Tg animals (B). Reactive microgliosis and astrocytosis were also associated with plaques (data not shown). C andD illustrate endogenous expression of APP in Wt animals (C) detected with a supraoptimal dilution of anti- human APP695 (22C11). D illustrates a high level of intraneuronal accumulation of APP in CA1 through CA4 cell body layers. Heavy labeling of plaques was also evident in subiculum, stratum oriens, stratum moleculare, and stratum granulosum of the dentate gyrus. Evident with plaque structures were intense punctate labeling indicative of type I dystrophic neurites (data not shown). Scale bar, 200 μm.