Fig. 12.

Schematic of the requirements of Pbx4 in OFT and great artery development. In WT embryos, nkx2.5⁺ cells within the ALPM separate into anterior populations that will primarily contribute to the heart tube and later to differentiating proliferative SHFPs, and posterior populations that will contribute to the pPAAs. In lzr mutants, the anterior and posterior nkx2.5⁺ populations initially fail to separate and later the SHFPs are more proliferative, leading to hearts with enlarged OFTs coupled with loss of the pPAAs. Blue, nkx2.5⁺ progenitors; purple, pPAA progenitors; orange, FHF progenitors forming a cone; red, ventricular CMs; green, atrial CMs; yellow, proliferating cells; light blue, aorta and pPAAs.