title: Asymmetric fate of the posterior part of the second heart field results in unexpected left/right contributions to both poles of the heart.
abstract: BACKGROUND
  The second heart field (SHF) contains progenitors of all heart chambers, excluding the left ventricle. The SHF is patterned, and the anterior region is known to be destined to form the outflow tract and right ventricle.
  
  
  OBJECTIVE
  The aim of this study was to map the fate of the posterior SHF (pSHF).
  
  
  RESULTS
  We examined the contribution of pSHF cells, labeled by lipophilic dye at the 4- to 6-somite stage, to regions of the heart at 20 to 25 somites, using mouse embryo culture. Cells more cranial in the pSHF contribute to the atrioventricular canal (AVC) and atria, whereas those more caudal generate the sinus venosus, but there is intermixing of fate throughout the pSHF. Caudal pSHF contributes symmetrically to the sinus venosus, but the fate of cranial pSHF is left/right asymmetrical. Left pSHF moves to dorsal left atrium and superior AVC, whereas right pSHF contributes to right atrium, ventral left atrium, and inferior AVC. Retrospective clonal analysis shows the relationships between AVC and atria to be clonal and that right and left progenitors diverge before first and second heart lineage separation. Cranial pSHF cells also contribute to the outflow tract: proximal and distal at 4 somites, and distal only at 6 somites. All outflow tract-destined cells are intermingled with those that will contribute to inflow and AVC.
  
  
  CONCLUSIONS
  These observations show asymmetric fate of the pSHF, resulting in unexpected left/right contributions to both poles of the heart and can be integrated into a model of the morphogenetic movement of cells during cardiac looping.
authors.affiliation: Division of Biomedical Sciences, St George's University of London, Cranmer Terrace, London SW17 0RE, United Kingdom.
authors.forename: Jorge N
authors.initials: JN
authors.lastname: Domínguez
authors.forename: Sigolène M
authors.initials: SM
authors.lastname: Meilhac
authors.forename: Yvette S
authors.initials: YS
authors.lastname: Bland
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Buckingham
authors.forename: Nigel A
authors.initials: NA
authors.lastname: Brown
mesh_terms: D000818:Animals; D021461:Animals, Outbred Strains; D054326:Coronary Sinus / Q000166:cytology / Q000196:embryology; D046149:Embryo Culture Techniques; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000502:physiology; D051526:Fibroblast Growth Factor 10 / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D006321:Heart / Q000196:embryology* / Q000502:physiology*; D006325:Heart Atria / Q000166:cytology / Q000196:embryology; D006352:Heart Ventricles / Q000166:cytology / Q000196:embryology; D007763:Lac Operon; D051379:Mice; D008822:Mice, Transgenic; D038081:Organogenesis / Q000502:physiology*; D019170:Somites / Q000166:cytology / Q000196:embryology
chemical_list: C496464:Fgf10 protein, mouse; D051526:Fibroblast Growth Factor 10