Fig. 3

Fig. 3

Early cardiomyocyte specification does not appear reduced in pbx4 mutant embryos. (A–F) RNA in situ expression at the 10 s stage of cardiomyocyte specification genes (A–B) gata4, (C–D) gata5, and (E–F) hand2 in the anterior lateral plate mesoderm (ALPM) in (A,C,E) control and (B,D,F) pbx4^b557-/- embryos. Expression of the Pbx-dependent gene krox20, marking hindbrain rhombomeres 3 and 5 (r3, r5 in A), was included to distinguish between control and pbx4^b557-/- embryos [12,19]. Arrows indicate ALPM expression domains in control embryos. The junction between hand2-expressing ALPM and posterior lateral plate mesoderm domains is noted by arrowheads (E). For (A–D), n e 10 for each marker in pbx4^b557-/- embryos and n e 30 for each marker in control embryos, all with similar expression patterns. For (E–F), pbx4^b557-/- embryos display expanded hand2 expression (n = 14; 13/14 with expanded expression) compared to control embryos (n = 47; all similar). Embryos are shown in dorsal view, anterior towards the left.