Fig. 1

Knockdown of cthrc1a disrupts epiboly and axis extension. (A–J) Representative live images of CoMO-injected and cthrc1MO-injected embryos. The white triangle marks the embryonic shield; red arrows indicate the blastoderm margin, and red arrowheads show the anterior tip of hypoblast; yellow lines define the angle formed between the dorsal side and the anterior tip of hypoblast, with vertex at the geometric centre of the embryo, which represents the extent of animal pole migration of the anterior tip of hypoblast. Embryos at 5.5 hpf, 7.5 hpf, and 10 hpf are positioned with animal pole on the top and dorsal region on the right, and embryos at 14 hpf and 26 hpf are lateral views. (K–P) In situ hybridisation of CoMO-injected and cthrc1MO-injected embryos using indicated markers, showing defective CE movements. Dorsal view for all embryos oriented anterior region up. (Q–V) Rescue of axis extension defects in cthrc1a morphants by myc-Cthrc1a at 10 hpf and 27 hpf. (W) Statistical analysis of the extent of hypoblast migration in embryos injected with CoMO, cthrc1MO, or coinjected with myc-cthrc1a and cthrc1MO. Bars represent the mean ± s.d. from three independent experiments (***, P < 0.001). Scale bars: (A-D, F–I, K–P, Q, S and U), 200 μm; (E, J, R, T and V), 500 μm.