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Figure 2. Ventral expression of Xhairy2b induces a secondary axis and inhibits ventralizing factors. A,B: Uninjected control embryo and Xhairy2b mRNA ventrally injected embryo, respectively, at stage 35. Xhairy2b mRNA ventral injection results in the induction of secondary axes lacking head structures (arrowhead). C: Transverse section of the embryo shown in B. Secondary axis (arrowhead) has neural tube and somitic mesoderm but lacks notochord. no, notochord, nt, neural tube, so, somite. D,D′′: Uninjected control embryos (D) and Xhairy2b mRNA (800 pg) ventrally injected embryos (D′′) are shown in vegetal view, dorsal side up at stage 10.5. D′′: Expression of organizer genes, follistatin (D′), frzb1 (E′), and admp (F′) is ectopically induced by Xhairy2b (arrowheads). G′: The expression of Xvent1 and Xvent2 in the ventral region (G,H) is reduced by Xhairy2b expression (G′,H′, arrowheads). |
