Fig. 4.
Migration of Hedgehog-marked cells into the pulmonary trunk. (A-E) Hh-receiving lineage marked by TM administration at E7.5 and E8.5 in R26RGli1-CreERT2 embryos and analyzed at E8.5 (A), E9.5 (B), E10.5 (C), E11.5 (D) and E12.5 (E). β-Galactosidase positive cells were identified by whole-mount (left, 4× magnification) or section (middle and right; 4× and 10× magnification, respectively) histology. At E8.5 and E9.5, marked cells are primarily outside of the heart, in the mesoderm surrounding the pharyngeal endoderm (Ph). By E10.5 and E11.5, marked cells populate the outflow tract, with a continuous population of marked cells from the pharyngeal endoderm to the outflow tract present at E10.5, and a larger proportion concentrating to the pulmonary side of the single outflow tract at E11.5. At E12.5, separate pulmonary and systemic trunks have formed and the marked cells primarily populate the pulmonary trunk. OFT, outflow tract; RV, right ventricle; PA, pulmonary artery; PT, pulmonary trunk.