Figure 6. Analysis of Pax3^Δ5/Ap2αΔ5 conditional knockouts.

(A–C) Ap2α^-IRESCre;R26R lineage mapping in wildtype embryos shows colonization of lacZ-positive cells in E8 neural folds (A) and E10.5 OFT (B,C). Note absence of lacZ cells in pulmonary trunk SHF-derived vascular smooth muscle (arrow in C). (D–G) Examination of lacZ spatiotemporal expression patterns in wildtype (D&E) and conditional Pax3^Δ5/Ap2αΔ5 mutant (E&G) embryos at E10.5. Note reduced CNC colonization of E10.5 mutant 4^th and 6^th PAA's (arrow in G) compared to wildtype (arrow in E). Conditional mutants also exhibit exencephaly (ex) and spina bifida (sb). (H–I) Histological analysis of transverse sections of embryos shown in (D&F). Reduced CNC colonization of OFT region in conditional mutant (I) compared to control (H). (J–M) Conditional E14.5 Pax3^Δ5/Ap2αΔ5 mutants display DORV and both the OFT vessels are abnormally aligned over the right ventricle (K) and VSD defects (M) when compared to control littermates (J,L). The aorta abnormally exits the Pax3^Δ5/Ap2αΔ5 mutant right ventricle (M) compared to the left ventricle in the control (L), and asterix in L indicates intact interventricular septum. Abbreviations: Ao, aorta; aAo, descending aorta; fore, foregut; lv, left ventricle; otic, otic sulcus (presumptive ear); rv, right ventricle. Scale bar J–M is 100μm.