Supramolecular Organization of Collagen Fibrils in Healthy and Osteoarthritic Human Knee and Hip Joint Cartilage
Fig 1
SEM images of normal human articular cartilage after enzymatic depletion of the proteoglycan moiety and chondrocytes.
(a) SEM image of the collagen fiber meshwork from knee surface articular cartilage shows (i) the 67 nm D-band periodicity, (ii) the hierarchical organization of 5–7 threads of prototypic fibrils forming an individual collagen fiber; note that each prototypic fibril exhibits the 67 nm D-band periodicity; and (iii) a twisting of the prototypic fibril along the long axis of roughly about 400 nm (white arrow). (b) SEM image of hip surface articular cartilage with untwisted fibers (white arrows). (c) Collagen fibers were labeled by collagen II antibodies with 18-nm gold particles attached and directly inspected in cartilage by SEM. (d) imaging of 18-nm gold particles using the backscattering electron (BSE) mode in the SEM on extracted collagen type II fibers. (e) Graph shows the increase of collagen fiber diameter with the number of prototypic fibrils. (f) Comparison between fiber diameters in each zone in hip articular cartilage and knee articular cartilage. Scale bars, 100 nm (a to d).