Research Papers

On the Biomechanics of Cardiac S-Looping in the Chick: Insights From Modeling and Perturbation Studies

[+] Author and Article Information
Ashok Ramasubramanian

Department of Mechanical Engineering,
Union College,
Schenectady, NY 12308
e-mail: ramasuba@union.edu

Xavier Capaldi

Department of Physics,
Union College,
Schenectady, NY 12308

Sarah A. Bradner, Lianna Gangi

Bioengineering Program,
Union College,
Schenectady, NY 12308

1Corresponding author.

Manuscript received July 13, 2018; final manuscript received March 4, 2019; published online March 27, 2019. Assoc. Editor: Jeffrey Ruberti.

J Biomech Eng 141(5), 051011 (Mar 27, 2019) (12 pages) Paper No: BIO-18-1324; doi: 10.1115/1.4043077 History: Received July 13, 2018; Revised March 04, 2019

Cardiac looping is an important embryonic developmental stage where the primitive heart tube (HT) twists into a configuration that more closely resembles the mature heart. Improper looping leads to congenital defects. Using the chick embryo as the experimental model, we study cardiac s-looping wherein the primitive ventricle, which lay superior to the atrium, now assumes its definitive position inferior to it. This process results in a heart loop that is no longer planar with the inflow and outflow tracts now lying in adjacent planes. We investigate the biomechanics of s-looping and use modeling to understand the nonlinear and time-variant morphogenetic shape changes. We developed physical and finite element models and validated the models using perturbation studies. The results from experiments and models show how force actuators such as bending of the embryonic dorsal wall (cervical flexure), rotation around the body axis (embryo torsion), and HT growth interact to produce the heart loop. Using model-based and experimental data, we present an improved hypothesis for early cardiac s-looping.

Copyright © 2019 by ASME
Your Session has timed out. Please sign back in to continue.


Manner, J. , 2000, “ Cardiac Looping in the Chick Embryo: A Morphological Review With Special Reference to Terminological and Biomechanical Aspects of the Looping Process,” Anat. Rec., 259, pp. 248–262. [CrossRef] [PubMed]
Manner, J. , Wessel, A. , and Yelbuz, T. M. , 2010, “ How Does the Tubular Embryonic Heart Work? Looking for the Physical Mechanism Generating Unidirectional Blood Flow in the Valveless Embryonic Heart Tube,” Dev. Dyn., 239, pp. 1035–1046. [CrossRef] [PubMed]
Taber, L. A. , 2006, “ Biophysical Mechanisms of Cardiac Looping,” Int. J. Dev. Biol., 50(2–3), pp. 323–332. [CrossRef] [PubMed]
Sylva, M. , van den Hoff, M. J. , and Moorman, A. F. , 2014, “ Development of the Human Heart,” Am. J. Med. Genet., Part A, 164(6), pp. 1347–1371. [CrossRef]
Hamburger, V. , and Hamilton, H. L. , 1951, “ A Series of Normal Stages in the Development of the Chick Embryo,” J. Morphol., 88(1), pp. 49–92. [CrossRef] [PubMed]
Bremer, J. L. , 1928, “ Experiments on the Aortic Arches in the Chick,” Anat. Rec., 37(3), pp. 225–254. [CrossRef]
Manner, J. , 2004, “ On Rotation, Torsion, Lateralization, and Handedness of the Embryonic Heart Loop: New Insights From a Simulation Model for the Heart Loop of Chick Embryos,” Anat. Rec., 278(1), pp. 481–492. [CrossRef]
Manner, J. , 2013, “ On the Form Problem of Embryonic Heart Loops, Its Geometrical Solutions, and a New Biophysical Concept of Cardiac Looping,” Ann. Anat., 195(4), pp. 312–323. [CrossRef] [PubMed]
Ramasubramanian, A. , Latacha, K. S. , Benjamin, J. M. , Voronov, D. A. , Ravi, A. , and Taber, L. A. , 2006, “ Computational Model for Early Cardiac Looping,” Ann. Biomed. Eng., 34(8), pp. 1655–1669. [CrossRef] [PubMed]
Ramasubramanian, A. , Nerurkar, N. , Achtien, K. , Filas, B. , Voronov, D. , and Taber, L. , 2008, “ On Modeling Morphogenesis of the Looping Heart Following Mechanical Perturbations,” ASME J. Biomech. Eng., 130(6), p. 061018. [CrossRef]
Shi, Y. , Yao, J. , Young, J. M. , Fee, J. A. , Perucchio, R. , and Taber, L. A. , 2014, “ Bending and Twisting the Embryonic Heart: A Computational Model for c-Looping Based on Realistic Geometry,” Front. Physiol., 5, p. 297. [CrossRef] [PubMed]
Ramasubramanian, A. , Chu-Lagraff, Q. , Buma, T. , Chico, K. , Carnes, M. , Burnett, K. , Bradner, S. , and Gordon, S. , 2013, “ On the Role of Intrinsic and Extrinsic Forces in Early Cardiac s-Looping,” Dev. Dyn., 242(7), pp. 801–816. [CrossRef] [PubMed]
Flynn, M. E. , Pikalow, A. S. , Kimmelman, R. S. , and Searls, R. L. , 1991, “ The Mechanism of Cervical Flexure Formation in the Chick,” Anat. Embryol., 184(4), pp. 411–420. [CrossRef] [PubMed]
Männer, J. , Seidl, W. , and Steding, G. , 1995, “ Formation of the Cervical Flexure: An Experimental Study on Chick Embryos,” Acta Anat., 152(1), pp. 1–10. [CrossRef]
Patten, B. M. , 1922, “ The Formation of the Cardiac Loop in the Chick,” Am. J. Anat., 30(3), pp. 373–397. [CrossRef]
Bayraktar, M. , and Manner, J. , 2014, “ Cardiac Looping May Be Driven by Compressive Loads Resulting From Unequal Growth of the Heart and Pericardial Cavity. Observations on a Physical Simulation Model,” Front. Physiol., 5, p. 112. [CrossRef] [PubMed]
Voronov, D. A. , and Taber, L. A. , 2002, “ Cardiac Looping in Experimental Conditions: Effects of Extraembryonic Forces,” Dev. Dyn., 224(4), pp. 413–421. [CrossRef] [PubMed]
Xu, G. , Kemp, P. S. , Hwu, J. A. , Beagley, A. M. , Bayly, P. V. , and Taber, L. A. , 2010, “ Opening Angles and Material Properties of the Early Embryonic Chick Brain,” ASME J. Biomech. Eng., 132(1), p. 011005. [CrossRef]
Zamir, E. A. , and Taber, L. A. , 2004, “ Mechanical Properties and Residual Stress in the Stage 12 Chick Heart During Cardiac Looping,” ASME J. Biomech. Eng., 126(6), pp. 823–830. [CrossRef]
Voronov, D. A. , Alford, P. W. , Xu, G. , and Taber, L. A. , 2004, “ The Role of Mechanical Forces in Dextral Rotation During Cardiac Looping in the Chick Embryo,” Dev. Biol., 272(2), pp. 339–350. [CrossRef] [PubMed]
Latacha, K. S. , Remond, M. C. , Ramasubramanian, A. , Chen, A. Y. , Elson, E. L. , and Taber, L. A. , 2005, “ Role of Actin Polymerization in Bending of the Early Heart Tube,” Dev. Dyn., 233(4), pp. 1272–1286. [CrossRef] [PubMed]
Le Garrec, J.-F. , Domínguez, J. N. , Desgrange, A. , Ivanovitch, K. D. , Raphaël, E. , Bangham, J. A. , Torres, M. , Coen, E. , Mohun, T. J. , and Meilhac, S. M. , 2017, “ A Predictive Model of Asymmetric Morphogenesis From 3D Reconstructions of Mouse Heart Looping Dynamics,” eLife, 6, p. e28951. [CrossRef] [PubMed]
Drake, C. J. , Wessels, A. , Trusk, T. , and Little, C. D. , 2006, “ Elevated Vascular Endothelial Cell Growth Factor Affects Mesocardial Morphogenesis and Inhibits Normal Heart Bending,” Dev. Dyn., 235(1), pp. 10–18. [CrossRef] [PubMed]
Harvey, R. P. , 1998, “ Cardiac Looping—An Uneasy Deal With Laterality,” Semin. Cell Dev. Biol., 9(1), pp. 101–108. [CrossRef] [PubMed]
Srivastava, D. , and Olson, E. N. , 1997, “ Knowing in Your Heart What's Right,” Trends Cell Biol., 7(11), pp. 447–453. [CrossRef] [PubMed]
van den Berg, G. , Abu-Issa, R. , de Boer, B. A. , Hutson, M. R. , de Boer, P. A. , Soufan, A. T. , Ruijter, J. M. , Kirby, M. L. , van den Hoff, M. J. , and Moorman, A. F. , 2009, “ A Caudal Proliferating Growth Center Contributes to Both Poles of the Forming Heart Tube,” Circ. Res., 104(2), pp. 179–188. [CrossRef] [PubMed]
Patten, B. M. , 1951, Early Embryology of the Chick, 4th ed., McGraw-Hill, New York.
Beloussov, L. V. , 1998, The Dynamic Architecture of a Developing Organism: An Interdisciplinary Approach to the Development of Organisms, Springer, Dordrecht, The Netherlands.
Hoyle, C. , Brown, N. A. , and Wolpert, L. , 1992, “ Development of Left/Right Handedness in the Chick Heart,” Development, 115(4), pp. 1071–1078. http://dev.biologists.org/content/115/4/1071 [PubMed]
Waddington, C. H. , 1937, “ The Dependence of Head Curvature on the Development of the Heart in the Chick Embryo,” J. Exp. Biol., 14, pp. 229–231. http://jeb.biologists.org/content/14/2/229
Deuchar, E. M. , 1971, “ The Mechanism of Axial Rotation in the Rat Embryo: An Experimental Study In Vitro,” J. Embryol. Exp. Morphol., 25(2), pp. 189–201. http://dev.biologists.org/content/25/2/189 [PubMed]
Männer, J. , Seidl, W. , and Steding, G. , 1993, “ Correlation Between the Embryonic Head Flexures and Cardiac Development: An Experimental Study in Chick Embryos,” Anat. Embryol., 188, pp. 269–285. [CrossRef] [PubMed]
Chen, Z. , Guo, Q. , Dai, E. , Forsch, N. , and Taber, L. A. , 2017, “ How the Embryonic Chick Brain Twists,” J. R. Soc., Interface, 13(124), p. 20160395. https://royalsocietypublishing.org/doi/10.1098/rsif.2016.0395
Manner, J. , Seidl, W. , and Steding, G. , 1995, “ The Role of Extracardiac Factors in Normal and Abnormal Development of the Chick Embryo Heart: Cranial Flexure and Ventral Thoracic Wall,” Anat. Embryol., 191, pp. 61–72. [CrossRef] [PubMed]
Wenger, T. L. , McDonald-McGinn, D. M. , and Zackai, E. H. , 2014, “ Genetics of Common Congenital Syndromes of the Head and Neck,” Congenital Malformations of the Head and Neck, Springer, New York, pp. 1–22.
van Straaten, H. , Hekking, J. , Consten, C. , and Copp, A. , 1993, “ Intrinsic and Extrinsic Factors in the Mechanism of Neurulation: Effect of Curvature of the Body Axis on Closure of the Posterior Neuropore,” Development, 117(3), pp. 1163–1172. https://www.ncbi.nlm.nih.gov/pubmed/8325240 [PubMed]
Hutchins, G. , Moore, G. , Lipford, E. , Haupt, H. M. , and Walker, M. C. , 1983, “ Asplenia and Polysplenia Malformation Complexes Explained by Abnormal Embryonic Body Curvature,” Pathol., Res. Pract., 177(1), pp. 60–76. [CrossRef]


Grahic Jump Location
Fig. 1

An overview of cardiac looping, based on drawings from Ref. [15]. During c-looping ((a) and (b)), the initially straight HT is transformed into a c-shaped configuration. During early s-looping ((b)–(d)), the developmental stage considered here, the distance between the arterial and venous poles is shortened and the primitive ventricle migrates from its initial position cranial to the common atrium to its definitive position caudal to it. Note: (1) the formation of body flexures which happen at the same time as s-looping. Cranial flexure (which causes the axes of the forebrain and the hindbrain to form a right angle) and cervical flexure (broad curve on the dorsal body wall) are indicated in (d). (2) Head torsion—unrotated embryo has both eyes visible (indicated by arrowheads in (b)) while the rotated embryo has only eye visible (single arrowhead in (d)). Please note that the diagrams contain dorsal views. While a control embryo and its heart loop are shown here, improper loops formed due to perturbations are shown elsewhere in the paper. V = Ventricle, A = Atrium. Somite counts are indicated in boxes to the left of the stage labels.

Grahic Jump Location
Fig. 2

Effect of impeding torsion on heart morphogenesis. For each time point, whole embryo (thin panels on the left) and isolated heart images are shown. ((a)–(d)) Control embryos. Note the formation of the normal cardiac s-loop with the ventricle moving inferior to the atrium (V = ventricle, A = atrium, C = conotruncus (outflow tract, arterial pole), and OV = omphalomesenteric veins, (inflow, venous pole)). When torsion is impaired by inserting an eyelash (indicated by arrows), two distinct topologies are observed. In a majority of the cases, a planar hairpin bend is observed ((a′)–(d′)). Although the arterial and venous poles of the heart tube can approach each other, no out-of-plane deformation is present (compare (d) with (d′)). In a few cases, a heart loop is formed on the left ((a″)–(d″)). Note that in both cases, there is considerable and easily visible untwisting of the heart at t =0+ when the eyelash is first inserted, showing clearly that removing body torsion untwists the heart tube and puts it in a planar configuration unsuitable for normal s-looping (transition from (a′) to (b′) and from (a″) to (b″)). Local embryo directions are shown in (b); Note that, as the embryo is partially rotated, the horizontal axis is the dorsal–ventral axis in the cranial portion, but it is the left–right axis in the caudal portion. L = left; R = right. Scale bar = 1 mm (whole embryo), 250 μm (heart close-ups).

Grahic Jump Location
Fig. 3

Effect of heart removal on the formation of cervical flexure. ((a)–(d)) Control embryo at time points indicated. Cervical flexure (section between black arrows in (a)–(d)) increases. ((a′)–(d′)) Embryo at a similar starting stage in which the heart has been removed at t = 0+ ((b′)). Cervical flexure (section between black arrows in (a′)–(d′)) can still occur without the aid of the looping heart. Most heart-free embryos regrew primitive tubular structures resembling the heart. Regrowth was most prominent in the caudal end of the heart tube remnant (white arrowhead in (d′)). Scale bar = 1 mm.

Grahic Jump Location
Fig. 4

Length and radius of cervical flexure. (a) Illustration of our methodology (Sec. 2.4). Least squares best-fit circle is shown. Arrows indicate the start and end of cervical flexure segment. (b) Box plot of cervical flexure lengths (measured using line integrals) at t = 0 and t = 10 h for control (CTRL) and heart-free cultures (EXPT). The box contains the middle 50% of the data and the whiskers contain the top and bottom 25%. Outliers are shown as open circles. The horizontal line and the circle within the boxes indicate the median and the mean, respectively. (c) Box plots of cervical flexure radii at t = 0 and t = 10 h. Scale bar = 1 mm.

Grahic Jump Location
Fig. 5

Heart removal does not inhibit head rotation and cranial flexure. ((a)–(d)) control embryo, ((a′)–(d′)) heart-removed embryo. The angle between the forebrain the hindbrain eventually becomes 90 deg indicating normal cranial flexure (shown by dotted white lines in (d) and (d′)), whereas both eyes are visible initially (arrowheads in (a), (a′)), by t = 10 h, head rotation is complete and only one eye is visible (single arrowhead in (d), (d′)). Scale bar = 1 mm.

Grahic Jump Location
Fig. 6

A physical model for the s-looping heart tube. The “goose neck” metal rod denotes the head and the rubber tube (black) denotes the heart. The tube and the rod lie against a white board, which denotes the structures at the dorsal side of the heart. (a)–(d) The baseline model. Head rotation (implemented by rotating the top end of the tube 90 deg and clamping) ensures that the cranial part of the tube is displaced backward compared to the caudal part ((a) → (b)). When this necessary step is completed, bending of the metal rod, which corresponds to cervical flexure, can twist the tube into a loop ((b) → (c) → (d)). In the absence of the crucial rotation step, no loop is formed; instead a hairpin bend results ((a′)–(d′)) as in experiment (compare topology in (d′) with Fig. 2(d′)). While rotation seems to be necessary for looping, the model shows that a basic loop can form in the absence of cervical flexure when the tube is allowed to elongate ((a″)–(d″)). A solid tube extracted from a hollow tube ((a″)) simulates growth. To start with, rotation is applied as in the baseline model ((a″) → (b″)). At this point, the rubber tube is allowed to “grow” by gradually pulling out the segment of the solid tube that is within the hollow tube. In (a″)–(d″), arrowheads show the extent of the solid tube that is inside the hollow tube.

Grahic Jump Location
Fig. 7

Finite element model of early cardiac s-looping in control conditions. Top row shows time progression of model while bottom row shows the experiment at comparable time points (whole embryo pictures are shown along with heart close-ups). ((a), (a′)) heart at t = 0 that is not rotated. Inset in model shows cross section where a thin layer of myocardium encloses a thicker layer of cardiac jelly (extracellular matrix) which in turn encloses a circular lumen. Curved arrow at top end shows the direction of head rotation. ((b), (b′)) heart when head rotation is completed. ((c), (d) and (c′), (d′)) gradual progression of cervical flexure brings together the conotruncus and the atrium and completes the loop. (V = ventricle, A = atrium, C = conotruncus (outflow tract, arterial pole), and OV = omphalomesenteric veins, (inflow, venous pole)).

Grahic Jump Location
Fig. 8

Finite element model of early cardiac s-looping when torsion is inhibited. Top row shows the time progression of the model while the bottom row shows the experiment at comparable time points (whole embryo pictures are shown along with heart close-ups). ((a), (a′)) Heart in embryo that has undergone torsion, but not flexure. ((b), (b′)) Heart configuration when head rotation has been removed (note inserted hair in experiment; rotational loads are removed in model). ((c), (c′) and (d), (d′)) Heart configuration when flexure is allowed to continue in the absence of torsion. Note the formation of the “hairpin bend” configuration in (d) and (d′). In this particular embryo, the conotruncus and the atrium do not touch each other at t = 10 h ((d′)), but they do in other embryos (please see Fig. 2(d′)). (V = ventricle, A = atrium, C = conotruncus (outflow tract, arterial pole), and OV = omphalomesenteric veins, (inflow, venous pole)). Scale bar in whole embryo pictures = 1 mm. Scale bar in heart close-ups = 250 μm.



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In