Fig. 6.

Myocardin is essential for cardiogenesis in chick embryos. A,B: Whole mount immunostaining of HH Stage 12 chick embryos using the MF20 monoclonal antibody, which specifically recognizes striated cardiac and skeletal muscle myosin heavy chain. The developing heart (arrow) and somites (arrowhead) are indicated. B: Higher magnification of (A). Chick embryos in new culture were microelectroporated with expression plasmids for either a wild-type myocardin (D) or a dominant negative mutant form of myocardin (H), or treated with antisense oligonucleotides specific for myocardin (F) or their respective controls (C, G, and E) as described in Materials and Methods. After incubation for additional 24 hr, embryos were harvested and analyzed by whole mount immunostaining using the MF-20 monoclonal antibody, which marks the cardiac structure (blue).