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A lineage tree for the myocardium of the heart and for nonsomitic head and neck muscles (in bold), based on retrospective clonal analyses in the mouse embryo. In the case of nonsomitic neck muscles, clonal analysis focused on the trapezius and sternocleidomastoid muscles. The two myocardial lineages can be compared with the two heart fields that constitute sources of equivalent parts of the myocardium. a, anterior; FHF, first heart field; p, posterior.
