Embryos were processed to show expression of notochord marker ntl (A–D, I–L), and somatic and pre-somitic mesoderm marker, papc (E–H). All embryos are 1-somite stage, and oriented with their animal pole toward top. Embryo in panel L was fixed at the time when control embryos reached 1-somite stage. All are dorsal views. Amount of each morpholinos injected are indicated in bottom left corner of each panel. Scale bar: 100 µm. M) Quantitation of length of dorsal midline ntl expression domain. The amount of morpholino in each case were as follows. Control-MO, 9 ng; fzd7a, fzd7b-MOs, 2 ng each; fzd7a, fzd7b, fzd10-MOs, 2, 2, 1 ng, respectively; fzd7a, fzd7b, fzd10-MOs, 2, 2, 2 ng, respectively; fzd7a, fzd7b, fzd10-MOs, 2, 2, 5 ng, respectively. P values estimated by Tukey's multiple comparison test are indicated for each pair. Error bars are s.e.m. for each group.