Fig. 6. Contribution of extracardiac cells from the AHF is unaffected in Hand1-overexpressing embryos. RNA in situ hybridisation analysis of Isl1 and Mef2c in control embryos (A,C,E,G,I,K) and moderate phenotype Hand1-overexpressing embryos (B,D,F,H,J,L) at E9.5. Right lateral views of whole-mount embryos (A,B,G,H). Sagittal sections of the control (C,E,I,K) and Hand1-overexpressing hearts (D,F,J,L). There are no apparent differences in expression of the AHF marker Isl-1 between control and overexpressing embryos (compare A,C,E with B,D,F) or in expression of markers of AHF derivatives, as indicated by Mef2c (compare G,I,K with H,J,L). aa, aortic arch(es); at, atrium; ba, branchial arch; co, control; oe, overexpression; oft, outflow tract; rv, right ventricle. Scale bars: 200 µm in A for A,B,G,H; 50 µm in E for C-F,I-L.