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Figure 2. Electron micrographs of the synovial membranes that face the joint compartment in synovitis-induced rat TMJs. The sections were prepared by the pre-embedding technique, with the same method and anti-nitrotyrosine antibody as in Figs. 1b and 1d. (a-d) Electron micrographs of synovial lining cells that face the joint compartment in synovitis-induced rat TMJs. (a,b) Ultrastructural localization of nitrotyrosine-immunoreactive products in the synovial type A cells (A cell). (b) High magnification of the synovial type-A cells. Nitrotyrosine-immunoreactive products are distributed widely in the cytoplasm of type A cells, with microvilli (small arrows) that protrude toward the joint compartment (JC). Nitrotyrosine-immunopositive products are present in the cytoplasm (white arrow) near the mitochondrion (M), vesicle (V), and vacuole (Va). The nitrotyrosine-positive vesicle (arrowhead) is fused with vacuoles. Nitrotyrosine immunoreactivity is also found on the plasma membrane of the cell (white arrowhead). The nitrotyrosine-positive reaction is also detected in the intercellular space of the synovial lining cells (arrow). (c,d) Ultrastructural localization of nitrotyrosine-immunoreactive products in the synovial type B cells (B cell). (d) Higher magnification of the region indicated by the arrow in Fig. 2c. Positive immunostaining for nitrotyrosine is found in the type B cells. Immunoreactive products (arrowheads) are present in the cytosol, vesicles, and rough endoplasmic reticulum (r-ER) within the cytoplasm. In the nuclei (N) of type B cells, many nitrotyrosine-positive products are deposited on the euchromatin of the nucleoplasm (large arrowheads). (e) Ultrastructural localization of nitrotyrosine-immunoreactive products in a fibroblast of the subsynovial layer. Nitrotyrosine immunoreactivity is evident in the cytoplasm (arrowhead) and nucleus (arrows). Not counterstained. Original magnification: (a,c,e) x5000; (b,d) x12,500. Bar = 1 µm (a,c,e) or 0.4 µm (b,d).
