Figure 1. Immunohistochemical overview for FGF-2, FGFR-1, VEGF, Flt-1, and CD34 of the synovial tissues. (A) FGF-2-stained sections obtained from a patient with internal derangement (insert, low power). (B) FGFR-1-stained sections obtained from the same patient (insert, low power). (C) VEGF-stained sections obtained from the same patient (insert, low power). Immunoreactivities for FGF-2, FGFR-1, and VEGF are observed in the synovial lining cells (large arrows), endothelial cells of the blood vessels (arrowheads), and fibroblasts (small arrows). (D) Flt-1-stained sections obtained from the same patient (insert, low power). Immunoreactivities for Flt-1 are observed in the endothelial cells of the blood vessels (arrowheads) and synovial lining cells (large arrows). (E) A specimen obtained from the same patient incubated with CD34 antibody (insert, low power). Beneath the synovial lining cells, lumen structures of various sizes are immuno-positive, making them easy to distinguish from other cells. (F) FGF-2-stained sections obtained from a control patient. Only a few immuno-positive cells were observed in the synovial lining cells (arrows). (G) FGFR-1, (H) VEGF, and (I) Flt-1-stained sections obtained from a control patient. No immunoreactivities are observed in the synovial tissue. (J) A control specimen incubated with CD34 antibody showing only a few immunopositive cells (arrows) (bar, 50 µm).