Fig. 3: Structural transformations of mineral in FE and TE samples.

A FIB-SEM images illustrating the progression of morphologies, distributions and assemblies of mineral particles at the FE and TE interfaces. B Corresponding enlarged BSE images at different sites in (A) showing multiple mineral particles with various morphologies dispersed in the matrix. C 3D rendering of typical mineral particles intersecting with FIB-SEM image planes at the mineralization front of the interface region, demonstrating the mineral appearance and aspect ratio in different samples. D 3D rendering of the mineralization front highlighting distinct mineral assembling patterns for FE and TE. Labeled (colored) mineral tesselles in relation to aspect ratio (unmineralized collagen digitally removed, right panel). E, F Distribution of mineral tesselle sizes generated from label analysis in FE and TE mineralization front obtained from right panel in (D). G The aspect ratio of mineral tesselles in FE and TE mineralization front (n = 64 from 3 donors/group). Each biological replicate is color-coded (orange, green, and purple), and the technical replicate values were separately pooled for each biological replicate and the mean calculated for each pool; those three means were then used to calculate the average (horizontal bar), standard deviation of the mean (error bars), and P value. Scale bar in (A): 2 μm; (D): 1 μm; (B, C, E, F): 200 nm. *P  <  0.05, G (P < 0.0001), unpaired two-tailed Student’s t test. Abbreviations, FE, ACL-femoral enthesis; TE, ACL-tibial enthesis. Source data are provided as a Source Data file.