Col4a6 and Col4a5 are required for BM integrity.

<p>Wild-type (A, D, E, J, L) and <i>col4a5</i> (B, F, G) and <i>col4a6</i> (C, H, I, K, M) mutant larvae at 5 dpf were stained with anti-laminin–1 (A-I), anti-HNK–1 (zn12, J-K), or anti-HSPGs (10E4, L, M) antibodies. (A-C, J-M) BM in the dorsal hindbrain. Dorsal views of the rostral hindbrain, optical sections. (D-I) BM in the tectal region. RGC axons marked by pou4f3:Gal4; UAS:GAP-GFP (green) were co-stained with an anti-GFP antibody in the tectum; dorsal projection views (D, F, H) and lateral views (E, G, I). The laminin–1⁺ BM structure was split in the dorsal hindbrain region of the <i>col4a5</i> and <i>col4a6</i> mutants (indicated by arrowheads, B, C). In the tectal region of these mutants, the laminin–1⁺ BM was split into two layers: one attached to the skin and the other located more internally with intermittent disruption (arrowheads, G, I). Some RGC axons were located in the interspace between the two BMs in the mutant tectum (indicated by arrows, G, I). Signals for HNK–1 and HSPGs (marked by arrowheads) in the dorsal hindbrain BM of the <i>col4a6</i> mutants (K, M) were weaker than in wild type (J, L). (N, O) Schematic drawing of head (N) and hindbrain (O) regions. The laminin–1⁺ structures are marked by brown lines and the BM surrounding the hindbrain is marked by arrowheads (O). The statistic analysis is shown in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1005587#pgen.1005587.s017" target="_blank">S4 Table</a>. Scale bars: 20 μm in C (applied to A, B); 20 μm in H (applied to D, F); 30 μm in I (applied to E, G); 20 μm in M (applied to J, K, L, M).