Fig. 1. Delta-Notch is required to maintain the spinal cord precursor pool and for OPC specification. All images show transverse sections, dorsal to the top. (A-C) 1 dpf embryos treated with BrdU and anti-BrdU antibody (pink) to mark S-phase cells and Hoechst (blue) to reveal nuclei. dla^-/-;dld^-/- (B) and mib^-/- (C) embryos had fewer S-phase spinal cord cells than wild type (A). Spinal cords are outlined. (D-F) 1 dpf embryos labeled with anti-phospho-histone-H3 antibody to mark M-phase cells (green) and pan neuronal anti-Hu antibody (red). dla^-/-;dld^-/- (E) and mib^-/- (C) embryos had excess neurons and a deficit of M-phase cells relative to wild type (D). (G-I) 2 dpf embryos probed for sox10 expression, which marks OPCs, by in situ RNA hybridization. Spinal cord cells of dla^-/-;dld^-/- (H) and mib^-/- (I) embryos did not express sox10. (J-L) 3 dpf embryos probed for plp1/dm20 RNA expression, which marks premyelinating oligodendrocytes. dla^-/-;dld^-/- (K) and mib^-/- (L) embryos did not express plp1/dm20. Scale bars: 20 µm.