lama5 is required for formation of the apical ectodermal fold. In situ hybridizations for msxc (A–D) and dlx2 (E–H) in wild-type (A, C, E, G) and lama5 mutant (B, D, F, H) embryos. msxc and dlx2 expression appear normal in mutant embryos at 36 hpf relative to wild-type expression at this stage. Note that at 48 hpf, msxc and dlx2 are expressed in lama5 mutants, but the pectoral fins fail to elongate and form apical ectodermal folds (compare panels D and H with panels C and G). Immunostaining for cadherin (red) in wild-type (I and K) and lama5 mutant (J and L) embryos at 48 hpf marks formation of the AEF in wild-type embryos (bracket in panel I). Epidermal cells in lama5 mutants fail to form an AEF and remain as a single epithelial layer (arrow in panel J). Views of epidermal cells in wild-type (K) and mutant (L) pectoral fins show the extended morphology of wild-type epidermal cells compared to mutant epidermal cells. Anterior is to the left, panels A–H are lateral views, panels I–L are dorsal views. Dashed lines in panels G and H show the plane of the confocal sections shown in panels I–L. DAPI-stained nuclei, pseudo-colored green for contrast, are shown in panels I and J.
|
