Characterizing the Contribution of First and Second Heart Field-derived Cells in Zebrafish Cardiac Development

Vertebrate heart development occurs through contribution from two spatio-temporally distinct progenitor populations termed the First Heart Field (FHF) and Second Heart Field (SHF). In the mammalian heart, the FHF gives rise to the left ventricle and parts of both atria, whereas the SHF contributes to the right ventricle, inflow and outflow tracts, and portions of the atria. Here I employed a cmlc2 driven CreERT and switch reporter lines to lineage trace the two populations in the adult zebrafish heart. Late differentiating cells, as displayed through EGFP-positive cells consistently made a significant contribution to the cortical layer of the adult heart, which has been shown to be a major source of new cardiomyocytes following cardiac injury. Cells derived from the proposed SHF population give rise to the primordial layer, as well as the trabeculae in the ventricular base. The cortical and primordial layers are partially derived from the SHF progenitor population.M.Sc