Fig. 7. Rescued neurons in the compact cell layer are calbindin-positive granule cells. (A,C) Low-power micrographs of reeler hippocampal cultures co-cultured next to the rat hippocampus to promote the formation of a dense neuronal layer (arrows) in the reeler cultures (staining for Neurotrace). (B) Boxed area in A counterstained for calbindin (red). Note that the neurons in the compact cell layer of the reeler culture are calbindin-positive, like the granule cells in the rat dentate gyrus. The dotted line represents the border between cultures. (D) Boxed area in C immunostained for calretinin (red). Only hilar neurons in the reeler mouse dentate gyrus are immunoreactive, indicating that these neurons do not participate in the formation of the densely packed cell layer (as a species difference, hilar mossy cells in the rat are not calretinin-positive). (E) Calretinin-immunopositive mossy cells (red) intermingle with granule cells in a slice culture of reeler hippocampus (culture from P0 mouse, DIV7; counterstained with Neurotrace, green). (F) High-power magnification of a calretinin-immunoreactive mossy cell (red) in the dentate area of a reeler culture (P0; DIV7). The cell was double-labeled for ApoER2 (green puncta). Scale bars: 200 µm in A,C; 85 µm in B; 55 µm in D; 80 µm in E; 4 µm in F.