Expression of <i>dlx5a</i> during early specification of median fin fold ectodermal cells.

<p>(A–C) <i>In situ</i> hybridization for <i>dlx5a</i> in zebrafish embryos from 15.5 hpf to 16 hpf: dorsal view of the posterior axis (A, C) and coronal section (A′) at the level indicated by the dashed line in (A). At 15.5 hpf, <i>dlx5a</i> is expressed in ectodermal cells at the lateral edges (le) of the neural keel (nk) underlying the periderm (pe) (A, A′) (the dashed line in A′ delineates the neural keel). From 15.5 hpf to 16 hpf, ectodermal cells expressing <i>dlx5a</i> follow a dynamic convergent movement to form the presumptive median fin fold (MFF) at the dorsal midline of the embryo (B–C). (D) Schematic representation of the zebrafish dorsal cellular movement implicating <i>dlx5a</i> based on A–C. The convergent movement produced by the establishment of the neural rod (nr) (16–19 hpf) leads to the fusion of the two lateral edges at the midline into the presumptive MFF expressing <i>dlx5a</i>. ep, epidermis; nc, notochord; psm, presomitic mesoderm; tb, tail bud. Scale bars shown in C for A–C and in A′ 50 µm.