Fig. 2

The mesoderm is not required for neural induction. Lateral views of live MZoep and MZoep;ntl double mutant embryos (A and B). The double mutant lacks tail somites but forms anterior neural tissue. The double mutant phenotype can be phenocopied by microinjection of ntl morpholinos into MZoep mutants (C and D). Analysis of the expression patterns of neural and mesodermal markers in MZoep and MZoep;ntl double mutants by whole mount RNA in situ hybridization. At 24 h, expression of emx1 and krox20 is indistinguishable in MZoep (E) and MZoep;ntl double mutant embryos (F). While MZoep mutants express markers of tail mesoderm including papc, α-tropomyosin, spt, and tbx6 (G, I, K, and M), these markers are all absent in MZoep;ntl double mutant embryos (H, J, L, and N). Early expression of otx2 during gastrulation is unaffected in MZoep;ntl double mutant embryos (P) compared to MZoep single mutants (O). The small otx2 domain in MZoep;dino embryos is not altered by treatment with ntl morpholinos (Q and R). A–F, 24-h embryos; G and H, lateral views of tails of 23 h, or, I and J, 24-h embryos; K and L, dorsal views of two-somite embryos, anterior is toward the top; M and N, lateral views of two-somite embryos; and O–R, dorsal views of mid-gastrula embryos (70% epiboly). Genotypes of all embryos were determined following photography by PCR-based analysis.