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Fig. 6
Gα13 expression prior to myocardial subduction is crucial for myocardial migration. (A-C) Classes of heart morphology phenotypes at 26 hpf, in embryos heat shocked at various stages: normal heart (A), two fused hearts (B) and two separated hearts (C). Arrowheads denote hearts. (D) Distribution of heart phenotype classes in embryos heat shocked at the indicated stages of development. The total number of embryos is indicated. *P<0.001; #P=0.8, percentage of normal-like embryos in indicated groups versus non-heat shocked group. (E) Model of how the endoderm and myocardial cells interact during heart-tube formation. The relative positions and velocities of migration of the endodermal sheet (green) and myocardial precursors (red dots) in control and S1pr2/Gα13-defective embryos at the indicated stages of myocardial-cell migration, with the mode of migration indicated. Arrow direction denotes direction of migration; arrow thickness indicates speed of migration.