Figure 6

BI formation and coronary vessels in ventricle septum. (A-C) Penetration distance from endocardium (Endo) and avascular distance from BI. n = 10. (D) Consecutive slides of Sema3d^LacZ/+ heart showing BI on epicardium (X-gal+) arises from endocardium and connects with chamber (double red arrow). (E) Majority of Endo-derived BIs appear on ventral side of ventricle septum (black lined area). *P < 0.05; n = 42. (F) Expansion of endocardium-derived ECs of BIs in Fog2 mutants. White dotted line indicates impaired SV-derived coronary plexus; white arrows indicate PECAM⁺ BIs. (G) In remote area of VS, endocardium sinusoids become narrow strand of PECAM⁺Lectin⁻ cells (white arrowheads), with loss of connection with chamber circulation. White dotted lines outline ventricle septum. Representative of three embryos. Black bar = 0.5 mm; white bar = 100 μm.