Abstract
Abstract: :
Purpose: In vitro production of fibrillar material resembling XFM has been demonstrated in two–dimensional culture of human Tenon¹s fibroblasts (HTF), but only microfibrils and not mature fibers. Method: Primary cultures of HTF from patients with (7 eyes) and without (6 eyes) XFS were established in MatrigelTM, a reconstituted extracellular matrix, in an attempt to confine secreted cellular products within the proximity of cells and to induce cellular differentiation. After 7–8 weeks of growth, Matrigel–embedded cells were examined by transmission electron microscopy (TEM) in a masked fashion. A whole cross section from each specimen, usually containing 50 to 100 cells, was examined, searching for exfoliation–like material around each individual cell present in the section. Results: Cells on the gel surface form multiple layers, while those within the gel appear solitary with long and slender cytoplasmic processes. Produced ECM contained membrane–like segments, amorphous material, and microfibrils (8–10 nm in diameter, hollow in cross section, occasionally reveal a banding pattern of 45–50 nm) resembling elastic microfibrils. There were no significant differences in appearance and quantity of microfibrils between control and EXF samples. In 2 out of 7 XFS samples, microfibrils appeared to aggregate into XF–like fibers with a diameter of 35 to 45 nm and banding periodicity of 50–60 nm. No such fibers were detected in control samples. The cells on the surface usually produced more matrix and were more uniformly involved than cells within the gel, although aggregation into XF–like fibers was only observed around cells within the gel. Conclusions: Three–dimensional tissue culture may be useful in studying the pathogenesis of XFS as well as other disorders of the extracellular matrix.
Keywords: microscopy: electron microscopy