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Updated: Jun 10, 2026

Ex Vivo Culture of Pharyngeal Arches to Study Heart and Muscle Progenitors and Their Niche
Published on: July 20, 2015
Early chordate origins of the vertebrate second heart field
Alberto Stolfi1, T Blair Gainous, John J Young
1Center for Integrative Genomics, Division of Genetics, Genomics and Development, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
Abstract:
The vertebrate heart is formed from diverse embryonic territories, including the first and second heart fields. The second heart field (SHF) gives rise to the right ventricle and outflow tract, yet its evolutionary origins are unclear. We found that heart progenitor cells of the simple chordate Ciona intestinalis also generate precursors of the atrial siphon muscles (ASMs). These precursors express Islet and Tbx1/10, evocative of the splanchnic mesoderm that produces the lower jaw muscles and SHF of vertebrates. Evidence is presented that the transcription factor COE is a critical determinant of ASM fate. We propose that the last common ancestor of tunicates and vertebrates possessed multipotent cardiopharyngeal muscle precursors, and that their reallocation might have contributed to the emergence of the SHF.
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