The Clonal Origin of Myocardial Cells in Different Regions of the Embryonic Mouse Heart

Abstract

When and how cells form and pattern the myocardium is a central issue for heart morphogenesis. Many genes are differentially expressed and function in subsets of myocardial cells. However, the lineage relationships between these cells remain poorly understood. To examine this, we have adopted a retrospective approach in the mouse embryo, based on the use of the laacZ reporter gene, targeted to the alpha-cardiac actin locus. This clonal analysis demonstrates the existence of two lineages that segregate early from a common precursor. The primitive left ventricle and the presumptive outflow tract are derived exclusively from a single lineage. Unexpectedly, all other regions of the heart, including the primitive atria, are colonized by both lineages. These results are not consistent with the prespecification of the cardiac tube as a segmented structure. They are discussed in the context of different heart fields and of the evolution of the heart.

Podoplanin deficient mice show a rhoa‐related hypoplasia of the sinus venosus myocardium including the sinoatrial node

“…These early observations on the addition of the secondary myocardium have recently been supported by several studies describing the addition of myocardium at the arterial pole, being secondary (Waldo et al, 2001) and anterior heart fields (Kelly et al, 2001;Mjaatvedt et al, 2001;Meilhac et al, 2004;Kelly, 2005) and the posterior heart field (PHF) at the venous pole (Cai et al, 2003;Meilhac et al, 2004;Christoffels et al, 2006;Gittenberger-de Groot et al, 2007) of the developing heart. The complete length of the splanchnic mesoderm contributing to the addition of myocardium at both poles of the heart was called second heart field (Cai et al, 2003) or second lineage (Cai et al, 2003;Meilhac et al, 2004;Kelly, 2005).…”

Clonal analysis reveals a common origin between nonsomite-derived neck muscles and heart myocardium

“…Because recombination is random, there is a low statistical probability that such an event occurs in the same location a second time, and therefore a cluster of labeled cells in the neck probably contains clonally related cells (23,43).…”

Genetics and Genetic Testing in Congenital Heart Disease

“…During the second and third weeks of human development, two mesodermal subpopulations, the first (FHF) and second (SHF) heart fields, contribute cells to the developing heart. While the FHF will ultimately contribute to the left ventricle and portions of the atria and right ventricle, the SHF supports development of the future outflow tract (OFT), ventricular septum, and the remainder of the atria and right ventricle 22 . Cells of the FHF originate in splanchnic mesoderm of the anterior lateral plate and in response to inductive signals from adjacent endoderm become the first cardiac precursors to differentiate 23 .…”