part of part of lateral plate mesoderm mesoderm-derived structure primary heart field A specific region of the lateral mesoderm that will form the primary beating heart tube. In mammals the primary heart field gives rise to the left ventricle. FHF PHF UBERON:0004140 XAO:0004185 first heart field heart field primary heart field this term denotes the primary heart field; GO:0003128 denotes the superclass of primary and secondary: specific region of the lateral mesoderm into the area which will form the primary beating heart tube[GO:0003138] uberon embryonic tissue anlage