Ultrastructural analysis of perlecan morphant embryos. (A and B) Parasagittal epon sections stained with toluidine blue from 4 dpf control (A) and MO-DV morphant embryos (B). Note the irregular structure and organization of the morphant's skeletal muscle and associated abnormal u-shaped myoseptal boundaries. The DA appears collapsed in the morphant and devoid of blood cells. NC, notochord; DA, dorsal aorta; PCV, posterior cardinal vein. (C–I) A comparison of morphant and control basement membrane structure. Electron microscopy of the vascular (C–E), epithelial (F and G), and notochord basement membranes (BM; H and I) suggest that morpholino-based perlecan knockdown does not compromise the integrity of the basement membrane. Bars: (A and B) 25 μm; (C–I) 1 μm.