(A–C) Expression of tcf7l1a mRNA at 24 hpf (A), and 36 hpf (B,C). (D–F) Expression of tcf7l1b mRNA at 24 hpf (D), and 36 hpf (E,F). Lateral whole-mount views are shown in (A,B,D,E) and cross-sections through the spinal cord are shown in (C,F) SC: spinal cord; NC: notochord. Scale bars = 20μM in C, 80μM in E.