title: The endoderm and myocardium join forces to drive early heart tube assembly.
abstract: Formation of the muscular layer of the heart, the myocardium, involves the medial movement of bilateral progenitor fields; driven primarily by shortening of the endoderm during foregut formation. Using a combination of time-lapse imaging, microsurgical perturbations and computational modeling, we show that the speed of the medial-ward movement of the myocardial progenitors is similar, but not identical to that of the adjacent endoderm. Further, the extracellular matrix microenvironment separating the two germ layers also moves with the myocardium, indicating that collective tissue motion and not cell migration drives tubular heart assembly. Importantly, as myocardial cells approach the midline, they perform distinct anterior-directed movements relative to the endoderm. Based on the analysis of microincision experiments and computational models, we propose two characteristic, autonomous morphogenetic activities within the early myocardium: 1) an active contraction of the medial portion of the heart field and 2) curling- the tendency of the unconstrained myocardial tissue to form a spherical surface with a concave ventral side. In the intact embryo, these deformations are constrained by the endoderm and the adjacent mesoderm, nevertheless the corresponding mechanical stresses contribute to the proper positioning of myocardial primordia.
authors.affiliation: Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Anastasiia
authors.initials: A
authors.lastname: Aleksandrova
authors.affiliation: Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA; Department of Biological Physics, Eotvos University, Budapest, Hungary.
authors.forename: Andras
authors.initials: A
authors.lastname: Czirok
authors.affiliation: Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Edina
authors.initials: E
authors.lastname: Kosa
authors.affiliation: Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Galkin
authors.affiliation: Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Tracey J
authors.initials: TJ
authors.lastname: Cheuvront
authors.affiliation: Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA. Electronic address: brongish@kumc.edu.
authors.forename: Brenda J
authors.initials: BJ
authors.lastname: Rongish
mesh_terms: D000818:Animals; D002465:Cell Movement; D002642:Chick Embryo; D003370:Coturnix; D004707:Endoderm / Q000166:cytology; D005109:Extracellular Matrix / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D006321:Heart / Q000196:embryology*; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism; D038081:Organogenesis
chemical_list: D005353:Fibronectins
keywords: Endoderm; Mechanics; Modeling; Myocardium