THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -The endocardium is a thin, smooth tissue that makes up the lining of the chambers and valves of the heart. The innermost layer of the heart’s walls, it serves as a barrier between cardiac muscles and the bloodstream and contains necessary blood vessels.

Detailed explanation-2: -The endocardium is built from epithelial tissue and is embryonically similar to the cells lining the blood vessels. In fact, endothelial cells make up the endocardium and this layer is continuous with the large blood vessels entering and exiting the heart.