Decreased number of NeuN-positive neurons in the hippocampi of <i>Rere</i>^om/eyes3 embryos.

<p>A) RERE immunohistochemistry analyses of mid-sagittal sections of the brain at E18.5. Lower panel (A’) is higher magnification of the boxed area in the upper panel, which includes the hippocampus. RERE (red color) is primarily expressed in Ammon’s horn of the hippocampus at E18.5. Scale bar = 100 µm. B) Brain sections through the hippocampi of wild-type and <i>Rere</i>^om/eyes3 embryos were probed with anti-NeuN antibody (green color) at E18.5. Decreased numbers of NeuN-positive cells are seen in CA fields of the hippocampus from <i>Rere</i>^om/eyes3 embryos compared to those from wild-type embryos. Scale bar indicates 50 µm. C) NeuN-positive cells in Ammon’s horn, including CA1, CA2, and CA3, and the dentate gyrus were counted and normalized to the area of each region. The number of NeuN positive neurons per area was significantly decreased in the Ammon’s horns of <i>Rere</i>^om/eyes3 embryos when compared to wild-type embryos (analysis based on fifteen slides containing at least three sections for each of three or more embryos; * = <i>p</i><0.01). D) Immunohistochemical analyses of brain section from E18.5 embryos probed using either an anti-cleaved Caspase-3 antibody and an anti-Phospho-Histone H3 (pHH3) antibody. Cleaved Caspase-3-positive cells were not detected in <i>Rere</i>^om/eyes3 embryos. Phospho-Histone H3-positive cells were identified in the dentate gyri (outlined with a dashed yellow line) of embryos of each genotype. Scale bar = 100 µm. E) Phospho-Histone H3-positive cells were counted and normalized to the area of the dentate gyrus including subgranularzone (analysis based on fifteen slides containing at least three sections for each of three or more embryos). The number of Phospho-Histone H3-positive hippocampal cells per µm² was not significantly different between wild-type embryos and <i>Rere</i>^om/eyes3 embryos. CA = cornu ammonis; Cp = cortical plate; DG = dentate gyrus.