Effects of VPA on differentiation and proliferation in cerebral cortex of the developing embryo. (A) Coronal sections of E15.5 rat embryo cerebral cortex immunofluorescently labelled for Tuj1 (green) and PCNA (red). (B) Rats at E13.5 of gestation were intravenously injected with 200 mg/kg VPA or PBS at 0 and 24 h and sacrificed. Immunofluorescence labeling of Tuj1 (green) and PCNA (red) was performed on coronal sections of embryonic brains of the E15.5 rat. The three layers of the cerebral cortex – the cortical plate (CP), the intermediate zone (IMZ), and the subventricular zone (SVZ) above the lateral ventricle (LV)- can be distinguished. The white arrow indicates the direction of migration of the differentiating cells (bar = 25 μm). (C) NPCs from E14 embryos were incubated in the presence of 10 ng/ml bFGF in the presence or absence of 1 mM VPA for 48 h. Immunofluorescence labeling was performed with anti-Tuj1 and anti-BrdU. Nuclei were counterstained with DAPI.