Fig. 2. CheWnt3 is required for the development of axial polarity and oral fates. (A) Gastrulation and elongation along the oral-aboral axis in a normal Clytia embryo (top row) was completely blocked in Wnt3-MO-injected embryos (bottom row), shown fixed at the early gastrula stage (15 hpf). (B) Complete loss of morphological axis in Wnt3-MO-injected embryos at late gastrula (20 hpf) stage. Cell contours were visualised by phalloidin (green) and nuclei by To-Pro3 (red). Gastrulation was severely delayed compared with uninjected embryos. The exact timing and site of residual cell ingression formation varied. (C) Equivalent 2-day-old planulae. No morphological oral-aboral axis is discernable in Wnt3-MO-injected embryos; however, endoderm formation has recovered. (D) Representative in situ hybridisation image of characteristic oral CheBra expression in early gastrulae (15 hpf) that is lost in Wnt3-MO-injected embryos. (E,F) Loss of CheBra expression in oral ectoderm, and of CheAxin in oral endoderm and ectoderm in Wnt3-MO-injected planulae (1.5 day). (G,H) Expansion of aboral FoxQ2A expression to nearly the entire body in Wnt3-MO-injected embryos fixed at early gastrula and planula stages (1.5 day). (I) Loss of expression of oral-ectoderm-expressed ligands CheWntX2, CheWnt9, CheWntX1A and CheWnt5 in Wnt3-MO-injected embryos fixed at the planula stage (1.5 day). Scale bars: 40 µm.