Skip to main content
. Author manuscript; available in PMC: 2016 Aug 1.
Published in final edited form as: Dev Biol. 2015 May 5;404(1):40–54. doi: 10.1016/j.ydbio.2015.04.016

Figure 5. Schematic representations of tissue movements in a ventral view.

Figure 5

5a – longitudinally incised myocardial field, as shown in Fig. 4D (embryonic left side; boxed area). The differentiating myocardium (dark green), contiguous with the surrounding non-cardiac mesoderm (light green), is undergoing contraction along its medial edge (indicated by a decrease in distance between the magenta arrows). At the same time, the myocardium actively generates bending moments (forces) that generate a groove (lower cyan arrows). The incision (red contour line) introduces an unconstrained boundary of the myocardium, which in turn bends and rotates medially (upper cyan arrow). The forces generated within the myocardial field posterior to the incision propel the myocardium anteriorly (blue segmented arrow) past the wound edge. 5b – medio-laterally incised myocardial field, as shown in Fig. 4E, with the same notations used as in panel 5a. The incision separates the myocardium and the adjacent non-myocardial mesoderm from the anterior tissues. As in 5a, tissue forces generated by the myocardial field posterior to the incision propels the myocardial tissue anteriorly (blue segmented arrow), past the wound edge. Tissue-autonomous bending moments drive the formation of characteristic spheres of myocardium at the wound edge. 5c: normal heart tube assembly. The myocardial field is located in the close vicinity of the AIP (purple semi-arch), and the mesoderm is overlain by the endoderm (the top light purple tissue layer), continuous with the AIP. The AIP endoderm undergoes a uniform contraction that moves both itself and the mesoderm mediocaudally (purple arrows). At the same time, the medial portion of the myocardial field actively contracts (pink arrows) and develops bending moments within the tissue. The mechanical constraints of the adjacent tissue transform this activity into the observed ventral bending (cyan arrows). The combination of these activities leads to the net displacement of the myocardial field in the anterior and medial direction, illustrated by the segmented arrow.