Fig. 1.

Morphological, colorimetric, and ultrastructural analyses of control and pathological joint connective tissues. In the top-left drawing, the site from which tissue samples were harvested is shown (encircled). H.E. (staining connective tissue in pink and cells nuclei in violet), M.T. (staining collagen in blue and muscle in red) (a, a′; c, c′; f, f′; i, i′; l, l′), and TEM ultrastructural analysis (o) of control connective tissues showed compact and well-organized collagen. A loose and disorganized connective tissue was instead visible in H.E.- and M.T.-stained pathological tissues (b, b′; d, d′; e, e′; g, g′; h, h′; j, j′; k, k′; m, m′; n-n′). Ultrastructural analysis at TEM (p, q, r) of pathological sections in different patients highlighted that collagen fibers lost the characteristic spatial organization (arrowhead in p, q, r). Bars in a–n′: 50 μm; bars in o–r: 500 nm