part of develops from ends during starts during cardiovascular system cardiac mesoderm tissue secondary heart field second heart field UBERON:0009889 SHF 2011-09-02T10:56:21Z xenopus_anatomy XAO:0004186 lab The population of cells located in the splanchnic mesoderm that contribute to the formation of the spiral septum of the outflow tract of the embryonic heart; it is located anterior to the primary heart field. NF stage 19 NF stage 33 and 34