Movie 1

Initially overlapping domains of otx2b-gbx1
Time-lapse imaging of otx2+(magenta) and gbx1+(cyan) cells in otx2b:HRAS- mKate2 and gbx1:Venus reporter lines. Embryos were dorsally mounted with the anterior end to the top and imaged from 10.5 hpf to 15 hpf. Tissue sections spanning about 20μm were chosen with a z interval of 1 μm. Images were acquired at 2:30 (min:sec) intervals. Maximum intensity projections (covering 3 μm) of the fluorescent images are shown. Overlapping expression domains of otx2b and gbx1 could be observed from the neural plate to the neural rod stages, as evidenced by the presence of cells that were positive for both mKate2 and Venus (double-positive).