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Fig. 4 wnt3a and wnt3a/wnt8 morphants lack mesodermal fates at the expense of floor plate in the caudal tail. All embryos were examined at approximately 27-28 hpf. More mildly affected wnt3a/wnt8 morphants that made some tail structures were selected for these analyses. (A-D) Tails of living 28 hpf embryos, anterior to the left. Arrows in B and D indicate premature termination of the notochord in wnt3a and wnt3a/wnt8 morphants, respectively, and the arrowhead in D marks enlarged neural tube lumen. (E-P) Embryos were fixed at 26 hpf and stained with the indicated marker. The caudal tip of the tail is outlined in black dashes for clarity where necessary. (E-H) Embryos stained with ntl to visualize the notochord, arrowheads indicate ntl expression in the tailbud; arrows in F and H indicate the tip of the truncated notochord. (I-L) α-tropomyosin staining to visualize the somites; arrowheads mark the posterior extent of somite formation. (M-P) Embryos stained for F-spondin to visualize the floor plate; arrow in P indicates the expanded floor plate in wnt3a/wnt8 embryos. (Q-T) Pan-neural ngn1 expression in the neural tube is unaffected by wnt3a and wnt8 inhibition.