− | The epicardium should consist of a single layer of epithelial cells in the normal heart with a similar layer lining the opposing pericardial surface. In this histological section there is an increase in cellularity of the epicardium with many inflammatory cells. | + | The epicardium should consist of a single layer of epithelial cells in the normal heart with a similar layer lining the opposing pericardial surface. In this histological section there is an increase in cellularity of the epicardium with many inflammatory cells and pink fibrin is visible. |