Fig. 5

Reduced cardiomyocyte differentiation at the venous pole in isl1 mutant embryos. (A-F) Single z-scan of the atrium of a representative isl1^K88X sibling (A-C) and mutant (D-F) embryo. White arrow (B) indicates eGFP^posDsRed^neg cardiomyocytes at the venous pole of the wild-type sibling heart; red arrow (E) indicates the venous pole of the isl1 mutant where only very few eGFP^posDsRed^neg cells are present. (G,H) Single z-scan of a confocal image at the level of the arterial pole showing the eGFP^posDsRed^neg cardiomyocytes in the isl1 mutant (white arrow). The region shown is similar to that of the control embryo shown in Fig. 2G-I. V, ventricle: A, atrium. Scale bar: 50 μm. (I) Schematic of the location of the eGFP^posDsRed^pos cells (yellow) and the eGFP^posDsRed^neg (green) cells in the arterial pole of the isl1 mutant. (J,K) The number of eGFP^posDsRed^pos (J) and eGFP^posDsRed^neg (K) cardiomyocytes per embryo. (K) The eGFP^posDsRed^neg cardiomyocytes are subdivided into eGFP^posDsRed^neg cells being present at either the arterial or the venous pole. Note the significant reduction of eGFP^posDsRed^neg cells at the venous pole in the isl1 mutants. Bars represent mean±s.e.m. ^**P<0.01.