Endocardial Cushion Cells (AEC)

Endocardial cushion cells sit within the cushion matrix. Before they detach from their epithelial layer and migrate to the cushion matrix, they begin to swell, while the cisternae of rough endoplasmic reticulum and golgi complex dilate. The cells then begin to separate and take on a mesenchymal appearance. Once the cells separate from the epithelial layer, they migrate to and situate themselves within the cardiac jelly formed by the myocardium.