Cardiac contraction is required for myocardial trabeculation. (A,D) Schematic diagrams of (A) morpholino (MO) injection at one-cell stage or (D) pharmacological inhibition of cardiac contraction (6µM blebbistatin) from 22hpf. The morpholino-injected or chemical-treated Tg(kdrl:EGFP); Tg(myl7:dsRed) double transgenic embryos were allowed to develop further and examined for cardiac trabecular phenotypes at 3dpf. (B,C,E) Maximal projection of confocal z-stacks reveals the overall shape of the heart. (B′,C′,E′) Mid-chamber confocal optical section of the same hearts shown in B,C,E. (B′′,C′′,E′′) Magnified high-resolution images of the cardiac regions marked by dotted lines in B′,C′,E′. White arrows point to trabeculae. a, atrium; v, ventricle. Scale bars: 50µm in C′,E′ 10µm in C′′,E′′.
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