Epicardial development

ABSTRACT

The physiological functions of the embryonic epicardium have been neglected for decades. However, we currently know that this tissue is an essential element in cardiac development. In this review we summarize the available knowledge about how the embryonic epicardium arises from an extracardiac progenitor tissue, the proepicardium, a cluster of coelomic cells that adhere to and spread over the myocardial surface. We describe the control, at molecular level, of the epicardial epithelialmesenchymal transition leading to the formation of the epicardial-derived cells (EPDC), which are highly invasive mesenchymal cells that invade the subepicardial space and the myocardium. We briefly discuss the developmental fate of the EPDC and their contribution to the development of the coronary vessels. Furthermore, epicardial cells and EPDC interact with the developing ventricular myocardium, promoting its maturation and growth, through a poorly-known mechanism that seems to be dependent on retinoic acid signaling. We finish this review with a discussion of the evolutionary origin of the proepicardium and epicardium, and their relationship with the primitive excretory system of vertebrates. This relationship can account for some of the peculiar features of epicardial development (AU)

RESUMEN

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