Suppressed Notch signal in the PS cDKO embryonic brain. The expressions of a notch ligand Dll1 and two notch downstream target genes, Hes1 and Hes5, were examined by in situ hybridization (A-F) and quantitative RT-PCR (G). The comparable E13.5 sections from the control and the PS cDKO brain were used. In all parts of the brain, the changes in the expression pattern were similar; the images in the lateral telencephalon are shown. (A, B) The Dll1 expression was increased in the PS cDKO. (C, D) Hes1 was expressed weakly in the control but decreased in the PS cDKO. (E, F) The Hes5 expression was strong in the control but decreased in the PS cDKO. (G) The expressions of the three genes were examined using real-time quantitative RT-PCR. n = 5 for each genotype. All RT-PCR results were concordant with the in situ hybridization results (*, p < 0.05; **, p < 0.01). Scale bar: 100 μm.