Fig. 6

BMP signaling is required cell autonomously for cardiomyocyte formation. (A, B) Example of transplantation results; lateral views, ventral to the top, anterior to the left. (A) Wild-type donor-derived cells expressing Tg(cmlc2:egfp) in wild-type host myocardium at 48 h.p.f. Scale bars represent 50 μm. (B) Overlay of bright-field and fluorescent images revealing that the donor-derived cells are located in the outer curvature of the ventricle. (C) Table of transplantation results indicating the frequency of myocardial contribution of wild-type donor cells or smad5 morphant donor cells in wild-type host embryos. Cells from smad5 morphant donors contribute significantly less often to myocardium than do cells from wild-type donors; asterisk indicates p < 0.05. In one example of smad5 morphant cardiomyocyte contributions, donor-derived cells were found in the ventricle; in the other example, donor-derived cells were found in both the atrium and the ventricle. (D, E) Detection of wild-type and smad5 morphant donor-derived cells in the skeletal muscle of wild-type host embryos at 48 h.p.f. by anti-fluorescein immunohistochemistry. Scale bars represents 50 μm. Lateral views, dorsal to the top, anterior to the left. (F) Table of transplantation results indicating the equivalent frequencies of skeletal muscle contribution of wild-type donor cells or smad5 morphant donor cells in wild-type host embryos. Differences between the frequency of wild-type contribution to myocardium and skeletal muscle are likely due to differences in organ field size. Since the skeletal muscle field is larger than the heart field (Kimmel et al., 1990), wild-type donor cells contribute to skeletal muscle more frequently.