Fig. 4

pdgfra is expressed within the ALPM while cardiac fusion is underway.

(A–D) Dorsal views, anterior to the top, depict pdgfra expression in wt embryos at 10 s (A), 12 s (B), 14 s (C), and 18 s (D). Arrows (A) indicate pdgfra expression in the ALPM and the neural crest (NC). Asterisk (D) denotes position of the myocardium by 18 s; although pdgfra is expressed in the myocardial precursors within the ALPM at earlier stages, its expression in these cells appears to be gone by this time point. (E–J) Comparison of hand2 (green) and pdgfra (red) expression patterns demonstrates their overlap in the wt ALPM at 10 s. (E–G) Three-dimensional confocal reconstructions of dorsal views, anterior to the top, focused on the left side of the ALPM (area outlined by a dashed box in (A). Arrows (E) indicate pdgfra expression in the ALPM and the NC. (H–J) Single transverse (XZ) sections from (E–G), respectively. Yellow arrow (H) indicates overlap of hand2 and pdgfra expression in the ALPM. (K–P) Comparison of axial (green) and pdgfra (red) expression patterns demonstrates lack of pdgfra expression in the axial-expressing anterior endoderm in wt embryos at 12 s. (K–M) Three-dimensional confocal reconstructions of dorsal views, anterior to the top; arrows (K) indicate pdgfra expression in the ALPM and the neural crest. (N–P) Single transverse (XZ) sections from (K–M), respectively. Arrowheads (N) indicate axial expression in the anterior endoderm, adjacent to, but not overlapping with, pdgfra expression in the ALPM. Scale bars: 60 μm.