Transmission Electron Microscopy Imaging and Quantification

Sample processing for transmission electron microscopy was performed as previously described (Georgiadis et al., 2016 (link)). Images were acquired with a JEOL JEM 1400 Plus transmission electron microscopy with a JEOL Ruby CCD camera (JEOL, Welwyn Garden City, United Kingdom). Consecutive 40 overlapping images covering 40 μm of a well-defined lamina densa were taken at ×15,000 magnification in a blinded fashion, where the identity of the samples was unknown during imaging, and AF quantification and unblinded only after those were completed. AF scoring was performed using established quantitative ultrastructural techniques (Tidman and Eady, 1985 (link)). Student’s t-test was used to carry out the statistical analysis.