Fig 1: Evaluation of isolated synovial fibroblasts from passage 3 using vimentin staining and CD90 detection by flow cytometry. (A and B) Isolated cells from synovial membranes of Sprague-Dawley rat knees (magnification, ×40). (C) Vimentin in the synovial cells was stained brown (magnification, ×100; immunocytochemical staining with diaminobenzidine chromogen). (D) PBS was used instead of vimentin staining to act as a negative control (magnification, ×100). (E) Cells were marked with homotype-negative phycoerythrin-labeled IgG antibody (negative control). (F) Positive cells marked with CD90 were detected by flow cytometry and indicated that the phenotype conformed to synovial fibroblasts. CD90, cluster of differentiation-90; IgG, immunoglobulin G.