Fig. 2. Dll1 expression and Notch1 activation are segregated into distinct cells in the VZ of the developing mouse telencephalon. (A-H) Brain sections from ICR mouse embryos at E13.5 were immunostained with anti-active Notch1 (actN1) and anti-Dll1 and TO-PRO-3 (nuclear staining). Higher magnifications of the boxed regions in C and G are shown in D and H, respectively. Arrowheads in D,H indicate Dll1-positive actN1-negative cells in the VZ. (I) The proportions of active Notch1-positive cells among Dll1-negative or Dll1-positive cells in the VZ of the neocortex were determined by immunohistochemical analysis. Data are the mean ± s.e.m. of values from three sections of each brain, and similar results were obtained from six independent brains. ^*P<0.0005. NCX, neocortex; GE, ganglionic eminence. Scale bars: 20 µm.