Methods summary. (a) Quail hearts were perfused with DiI, (b) optically cleared, (c) and imaged using confocal microscopy to detect both coronary microvasculature and cardiac nuclei. (d) Vessels were segmented, (e) and automatically skeletonized resulting in vessel-nodes, -segments and -points exported for analysis. A vessel-vector (red arrow) was defined for each vessel by connecting the start and end nodes. (f) The helical angle (αH) was calculated for each vessel-vector based on its position with respect to the heart’s surface. (g) Cardiac nuclei were imaged with DAPI. (h) A Fourier transform (FFT) was applied to each image and the resulting spectrum was multiplied by (i) a series of masks with different axial angles. (j) The resulting angular amplitude A(θi) was plotted as a function of angle, (k) and fit to a von Mises distribution.