Mef2cb regulates late myocardial cell addition from a second heart field-like population of progenitors in zebrafish

► The second heart field (SHF) is a source of heart muscle added to the developing heart. ► Defects in SHF development are causative for a number of congenital heart defects. ► We examine if SHF-like cells exist in the zebrafish. ► We describe a population of cells in zebrafish with SHF properties. ► Zebrafish may therefore provide a suitable model for SHF development.