Fig. 6

Fig. 6 lama5 mutants have severe disruptions in epidermal organization. Transmission electron micrographs of transverse sections of the fin fold at 48 hpf in wild-type (A) and lama5 mutants (B–D). Wild-type tissue is highly organized with an outer epithelial layer (enveloping layer, yellow brackets in panels A–C) containing microridges (arrowheads) and a basal epidermal layer (green brackets in panels A–C). Large collagen bundles, termed actinotrichia (Act), run along the length of the fin fold and are shown in cross-section separating the epidermal layer from migrating mesenchymal cells (M). lama5 mutants have major defects in epidermal architecture. Cells in the inner (green brackets) and outer epidermal layers (yellow brackets) have severe morphological and adhesion defects. Large cavities appear at cell–cell boundaries (red arrowheads in panels B and C) and ECM accumulates in the sub-epidermal space (blue bracket, B). Actinotrichia are present in mutants but are reduced in size and do not localize adjacent to the basal epidermal layer. Epidermal cells can be observed wrapping around the actinotrichia (D), a cell behavior never observed in the wild-type. N, epidermal nuclei.