Fig. 5.

Lineage tracing of ventricular myocardium and endocardium. a, c The atrial, ventricular walls and outflow tract walls, including the myocardium and endocardium, are composed of cells from the Nkx2–5-Cre expressing lineage at E10.5 (green). b In contrast, Mef2c-AHF-Cre-expressing cells make only a minor contribution to the left ventricular myocardium and part of the right atrial roof (arrows). d Mef2c-AHF-Cre-expressing cells (arrows) form the right ventricle and outflow tract, and outflow endothelium (arrowheads), indicating origin from the SHF. e Tie2Cre is expressed in all of the cells in the left ventricular endocardium at E10.5, whereas Mef2c-AHF-Cre is expressed in only a small number (f). These patterns of staining for Tie2-Cre (g-i) and Mef2c-AHF-Cre-expressing cells (i, j) are maintained at E15.5, with Mef2c-AHF-Cre labelling only a small portion of the endothelial cells in the left ventricle. RA right atrium, LA Left atrium, RV right ventricle, LV left ventricle, OFT outflow tract