Dermal bones of the mandibular arch and their transformations in edn1 mutants. Anterior is to the top. The wild-type (WT) maxilla (max) and dentary (den) are shown in right-side view (dorsal to the right) (A) and ventral view (B). (C-E) Three examples of the AP-reversed wicket phenotype in three individual edn1 mutants, that we interpret to include the malformed bilateral rudiments of the maxillas and dentaries, completely fused (C), or incompletely fused together (D,E) (ventral views, see also Fig. 2 for orientation). The arrows in D and E indicate variably present gaps along the wicket arms. In examples not shown with only mild reduction of Edn1 (as obtained in sturgeon mutants or when edn1-MO is injected at low levels), the maxilla and dentary are frequently normally shaped, but misoriented: the orientation relates to the change in the shape of the mouth, as in edn1 mutants. Injected at higher levels, edn1-MO yields the wicket phenotype, phenocopying the edn1 mutants, and a yet more extreme phenotype in which only a small bone fragment is present (data not shown). This remaining element is usually located at an anterior position in the wall of the mouth, suggesting that it is a remnant of the maxilla. Scale bar: 100 μm.