Figure 4

Hippocampal 7B7-A3 labeling in different avian species. Schematic representations of a coronal brain section of the (a) rock pigeon, (d) zebra finch, and (g) domestic chicken. The hippocampus is highlighted in grey; insets are shown on the right. Staining with 7B7-A3 antibody in the pigeon leads to robust nuclear staining within the entire (b) hippocampus and (c) parahippocampal area. In the zebra finch, hippocampal neurons show only sparse ZENK staining (e), while robust nuclear signal can be detected in the mesopallium as well as in the (f) parahippocampal area. In the chicken, 7B7-A3 stains the (h) hippocampus uniformly, but less intensely than those cells in the (i) parahippocampal area. Scalebars represent 2 mm in (a), (d), and (g); and 100 μm in (b), (c), (e), (f), (h), and (i).