Figure 8
From: Subepicardial endothelial cells invade the embryonic ventricle wall to form coronary arteries
Second heart field (Isl1, Tbx1, and Mef2c)-traced endocardial cells do not adopt a coronary EC fate. (A) Schematic illustrating the experimental design for testing the contribution of endocardial cells to coronary vessels in the embryonic ventricle wall. Endocardial cells and their progenies are labeled in red. (B) Isl1-Cre labeled NFATc1+ endocardial cells at E10.5 (yellow arrowheads). Dotted white line outlines the epicardium (left panel). Whereas Isl1-Cre labeled endocardial cells at E10.5, intramyocardial coronary ECs were not labeled at E15.5 (white arrowheads, right panel). Inset shows percentage of Isl1-Cre-traced cells (GFP+PECAM+) in both compartments. CA, coronary artery; Endo., endocardium. *P< 0.05; n = 6. (C, D) Neither Tbx1-Cre nor Mef2c-Cre lineage-traced endocardial cells contribute to intramyocardial ECs in the compact myocardium at E15.5 (white arrowheads). (E) Right lateral whole-mount view of Mef2c-Cre;Rosa26RFP/+ heart shows an unlabeled mature right CA (white arrowheads). (F) Mef2c-Cre labeled endocardial cells and coronary ECs in the VS at E15.5, but very few coronary ECs in the ventricle wall (RV). *P < 0.05; n = 4. White bar = 100 μm; red bar = 1 mm. LV, left ventricle; RV, right ventricle; VS, ventricular septum; Epi, epicardium; Endo., endocardium; Comp., compact layer; Trab., trabecular layer.
