English: Myofibril organization in an equilateral triangular muscle cell. The positive feedback loop between assembly of contractile elements and FA maturation permits continued lengthening of the contractile fibers, with the longest dimension of the cell acting as the only limiting factor to fiber elongation. This is demonstrated in Video S1, where nascent myofibril bundling and orientation were initially random (t = 0); as time elapsed, they reoriented themselves and were stabilized along the cellular peripheries at t = 120au. The color scale and lines represent the degree of parallel coupling and local orientation of myofibrils, respectively; color values are in arbitrary units.