Patterns of muscular strain in the embryonic heart wall.
The hypothesis that inner layers of contracting muscular tubes undergo greater strain than concentric outer layers was tested by numerical modeling and by confocal microscopy of strain within the wall of the early chick heart. We modeled the looped heart as a thin muscular shell surrounding an inner layer of sponge-like trabeculae by two methods: calculation within a two-dimensional three-variable lumped model and simulated expansion of a three-dimensional, four-layer mesh of finite elements. Analysis of both models, and correlative microscopy of chamber dimensions, sarcomere spacing, and membrane leaks, indicate a gradient of strain decreasing across the wall from highest strain along inner layers. Prediction of wall thickening during expansion was confirmed by ultrasonography of beating hearts. Degree of stretch determined by radial position may thus contribute to observed patterns of regional myocardial conditioning and slowed proliferation, as well as to the morphogenesis of ventricular trabeculae and conduction fascicles. Developmental Dynamics 238:1535-1546, 2009. (c) 2009 Wiley-Liss, Inc.
Department of Cell Biology and Anatomy, Medical University of South Carolina, Charleston, South Carolina, USA.
Brooke J
BJ
Damon
Mathieu C
MC
Rémond
Michael R
MR
Bigelow
Thomas C
TC
Trusk
Wenjie
W
Xie
Renato
R
Perucchio
David
D
Sedmera
Stewart
S
Denslow
Robert P
RP
Thompson
D000818:Animals; D002642:Chick Embryo; D004452:Echocardiography; D006321:Heart / Q000033:anatomy & histology / Q000196:embryology; D006352:Heart Ventricles / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000196:embryology; D008955:Models, Cardiovascular; D009200:Myocardial Contraction / Q000502:physiology; D012518:Sarcomeres / Q000000981:diagnostic imaging / Q000378:metabolism; D013314:Stress, Mechanical