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Early Mesodermal Cues Assign Avian Cardiac Pacemaker Fate Potential in a Tertiary Heart Field

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Science  21 Mar 2013:
1232877
DOI: 10.1126/science.1232877

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Abstract

Cardiac pacemaker cells autonomously generate electrical impulses that initiate and maintain the rhythmic contraction of the heart. Although the majority of the heart is thought to originate from the primary and secondary heart fields, we report that chick pacemaker cells arise from a discrete region of mesoderm outside of these fields. Shortly after gastrulation, canonical Wnts promote the recruitment of mesodermal cells within this region into the pacemaker lineage. These findings identify the ontogeny of cardiac pacemaker cells, suggesting that pacemaker cells are physically segregated and molecularly programmed in a tertiary heart field, prior to the onset of cardiac morphogenesis.

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