Epicardial outgrowth inhibition leads to compensatory mesothelial outflow tract collar and abnormal cardiac septation and coronary formation

In the present study, we investigated the modulatory role of the epicardium in myocardial and coronary development. Epicardial cell tracing experiment s have shown that epicardium-derived cells are the source of interstitial m yocardial fibroblasts, cushion mesenchyme, and smooth muscle cells. Epicard ial outgrowth inhibition studies show abnormalities of the compact myocardi al layer, myocardialization of cushion tissue, looping, septation, and coro nary vascular formation. Lack of epicardial spreading is partly compensated by mesothelial outgrowth over the conotruncal region, Heterospecific epica rdial transplant is able to partially rescue the myocardial development, as well as septation and coronary formation.