immunohistochemistry in human hippocampus. A. γ4 immunoreactivity was seen throughout the pyramidal cell layers each region of Ammon's horn and the surrounding neuropil with staining most intense in the CA2/3 transition region. Labeled regions are as in figures 4 and 5 with the addition of subiculum (s) choroidal fissure (cf) and fimbria (f). B. Section adjacent to that in panel A incubated with immunizing peptide pre-absorbed γ4 Ab. C. CA1 pyramidal cell bodies are moderately to strongly stained by γ4 Ab with moderate staining in surrounding neuropil. D. Strong staining of pyramidal cells in the CA3 with only slightly weaker immunostaining in the neuropil. E. Staining of CA4 cell bodies is moderate to strong with moderate neuropil staining. F. Although positively stained, the granule neurons of the dentate gyrus do not stain as strongly for γ4 as do pyramidal cells. Scale bars in panel A and B represent 5 mm and in panels C–F 25 μm.