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Figure 6. Expression of Xsm alpha -actin in developing Xenopus laevis embryos. A-D: Lateral and ventral views of late tail bud embryos (stage 26/27) after whole mount in situ hybridization to detect smooth muscle alpha -actin (Xsm alpha -actin; A,B) and cardiac alpha -actin (Xc alpha -actin1; C,D) gene expression. Although transcripts from both genes are colocalized in the bilateral domains of the heart-forming (h) region in these embryos, Xsm alpha -actin mRNA, unlike Xc alpha -actin1 mRNA, is not present in the somites (s). E: A lateral view of a stage 31 Xenopus embryo showing that Xsm alpha -actin expression is throughout the developing heart tube. F,G: Lateral views of the anterior portion of Xenopus embryos at stages 34 (F) and 41 (G) showing that Xsm alpha -actin transcripts are throughout the heart, up to and including the onset of chamber formation. H: In situ hybridization of a cross-section through the heart of a stage 59 tadpole showing that after the heart chambers [atria (a) and ventricle (v)] are formed Xsm alpha -actin transcripts are confined to the outflow tract (oft) of the heart. I: A higher magnification image of the outflow tract seen in H. |
