Endocardial Cushion Development

Endocardial cushions formation.

A-F. Steps in the formation of endocardial-derived cushion cells. At a specific developmental stage, a unique extracellular matrix ('cardiac jelly') is secreted by myocardium to the intramyocardial-endocardial space. This matrix induces an epithelial–to-mesenchymal transformation (EMT) of the endocardium, resulting in the generation of migrating endocardial cushion cells required for cardiac septation in the outflow tract (i.e., outflow cushion) and between the atria and the ventricle (i.e., atrioventricular cushion).