Fig. 2: Scaling properties of adult human muscle are similar to mice in spite of differences in absolute numbers.

a–d Representative image from muscle cells (n = 267) from the human v. lateralis labeled with DAPI to visualize nuclei (a). b Nuclear number was quantified by assigning a spot (red) to each nucleus. c Background fluorescence was used to automatically 3-D render the cells´ morphology. d Shows a 3-D rendered transparent muscle cell with its nuclei. e, g, i, and k Highlights the mean (arithmetic) value per muscle (n = 7), while f, h, j and l show the frequency distribution per fiber (n = 267), for cross-sectional area (e, f), nuclear number per mm (g, h), domain volumes (i, j) and surface domains (k, l). m Nuclear number per mm versus cross-sectional area tested against linear scaling (b = 1, dashed blue line). Comparison of fits gave a F-value of 82.39 (p < 0.0001). n Nuclear domains versus cross-sectional area were tested against the dashed line which indicate a fixed scaling (b = 0). Comparison of fits gave the F-value of 101.1 (p < 0.0001). o Nuclear number versus cell volume plotted and analyzed in log–log space gave a slope of b = 0.66 (95% CI: 0.60, 0.72). p Nuclear number per mm versus the fiber perimeter were statistically tested against a linear relationship (dashed blue line). Comparison of fits yielded a F-value of 5.967 (p = 0.0152). q Surface domains versus cross-sectional area tested against a horizontal slope (b = 0, dashed blue line), gave an F-value of 29.55 (p < 0.0001). r Nuclear number versus surface area plotted in log–log space gave a slope of b = 1.16 (95% CI: 1.03, 1.28). Error bars in e, g, i, and k represent the 95% CI’s, while the non-linear lines (purple) in h, j, and l were fitted by a Gaussian function, and f by a locally weighted smoothing regression (LOWESS). In m–r regression lines were fitted with an OLS method with (1, 265) degrees of freedom and compared with extra sum-of-squares F-test. Scale bars, 40 μm in a–d. Source data are provided as a Source Data file.