part of start stage end stage cardiovascular system portion of tissue proepicardial cluster ZFA:0005808 proepicardium Ceri 2014-07-28T03:01:42Z Transient cluster of cardiac progenitor cells that develops adjacent to the heart and migrates onto the heart to form the epicardium. Proepicardial clusters in Zebrafish form on the pericardial wall, adjacent to the atrioventricular (AV) junction and near the venous pole. zebrafish_anatomy proepicardial organ Appears after cardiac looping ~30hpf. Derived from mesoderm. unknown larval:protruding-mouth