Development of Heart in Amphibians
The heart and the surrounding pericardial cavity build up from lateral mesoderm. After gastrulation, the mesodermal mantles carry on to grow anteriorly and ventrally. At the ventral ends of these mantles below the gut and in the space among them there occurs proliferation of cells which initially make a cord but subsequently the cord of cells hollows out to form a tube. The tube made up of endothelial cells is called endocardium, meaning the inner lining of heart. Identical endothelial tubes are present anterior and posterior to endocardium and these tubes will become the major blood vessels to and from heart.