Formation And Contribution Of Intrapericardial Arterial Epicardium Of Mouse Embryonic Heart

Objective:To investigate the origin and formation of intrapericardial arterial epicardium(a EP)and its role in the development of intrapericardial aorta and pulmonary artery wall of mouse embryo.Methods:The paraffin-embedded serial sections of E9.5-E16 mouse embryos were stained with immunohistochemistry and immunofluorescence.The primary epicardial progenitor cells from the intrapericardial aorta and pulmonary artery tissue of E13 mouse embryos were extracted and cultured for immunofluorescence staining.Results:In E9.5-E10.5 mouse embryos,the epicardium gradually formed and distributed on the outer surface of atrium,atrioventricular canal and ventricular wall,but the epicardium of outflow tract(OFT)wall had not yet formed.In E11-E11.5 mouse embryos,the non-myocardial part of the OFT was gradually separated into the intrapericardial ascending aorta and pulmonary artery trunk,and the a EP began to appear in the dorsal wall of the pericardium and the distal end of the OFT wall connected to it.During E12.5-E16,the aorta and pulmonary artery was completely separated,progenitor cells of second heart field and a EP differentiated into smooth muscle cells,epicardial cells derived from the a EP can also be seen in the arterial valve.Conclusion:The epicardium of the non-myocardial part of mouse embryonic OFT comes from the mesoderm of the dosal wall of pericardial cavity in the arterial pole of the embryonic heart.Mesenchymal cells derived from the a EP can enter the media of the arteries,participate in the development of arterial wall and the development of arterial valve at the same time.