Figure 2.

The drawing shows the angles used to define the three-dimensional orientation of the aggregated cardiomyocytes. Plane A is the circumferential-longitudinal plane parallel to the epicardium, while plane B is the radial-longitudinal plane. Plane B is parallel to the left ventricular long axis, and orthogonal to plane A. The third plane, C, is the circumferential-radial plane, which is orthogonal to planes A and B. The helical angle α is the angle between the chain of aggregated cardiomyocytes (yellow rod) and plane C. The transmural angle β is the angle between the chain and plane A. The E3 angle γ is measured as the angle between the aggregate and the circumferential-longitudinal plane. The unit of aggregated cardiomyocytes, depicted as a flat box, is a gross oversimplification of the true three-dimensional arrangement.