Figure 8

Analysis of cardiac mesoderm and myocardium formation in cbs mutants. (A,B) WISH upon E9.5 wild type (+/+) and cbs/cbs embryos using probes recognizing Hand1 (A) and Nkx2.5 (B). The left side of the embryo is shown. Ventral is to the top, cranial is to the right. Arrow indicates signal in the left side of the heart tube. (B) With Nkx2.5, signal is also seen on the right side of the heart tube (data not shown). (C) anti-Islet 1 staining (Isl1, red) indicates Islet 1-positive precursors in the splanchnic mesoderm in both wildtype (+/+, c) and cbs/cbs (d) E10.5 embryos. *: non-specific signal at the apical edge of the common foregut tube epithelia. (D,E) Transverse sections of (D) E10.5 and (E) E12.5 wild type (+/+) and cbs/cbs embryos stained with an anti-α-actinin antibody (red) to label myocardial heart tissue. Dorsal is to the top, left is to the right. Sections were stained with DAPI to label nuclei. Note the relative lack of trabeculation in the presumptive ventricles (Lv, Rv, presumptive left and right ventricle, respectively) of the cbs/cbs heart at E10.5. Scale bars: A,B, 200 μm; C, 20 μm; D,E, 100 μm. cbs, cobblestone; DAPI, 4’-6-diamidino-2-phenylindole; E9.5,embryonic day 9.5; WISH, whole mount in situ hybridization.