Figure 1From: Characterisation of the cannabinoid receptor system in synovial tissue and fluid in patients with osteoarthritis and rheumatoid arthritisRepresentative haematoxylin and eosin micrographs of synovium biopsies taken at osteoarthritis or rheumatoid arthritis total knee arthroplasty. (a-c) Osteoarthritis: (a) category 1 (least inflamed), (b) category 2, and (c) category 3 (most inflamed). I, synovium intima; L, lymphoid body; SV, small vessel; V, villus. (d) Rheumatoid arthritis, category 3. Each biopsy was assigned to one of four categories: 0 = normal: synovial intima less than four cells thick, sparse cellular distribution, with few or no inflammatory cells (not shown as normal synovial fluid samples were not accompanied by synovium biopsies); 1 = mild inflammation: synovial intima three to five cells thick, slight increase in cellularity with few inflammatory cells; 2 = moderate inflammation: synovial intima four to six cells thick, dense cellularity with inflammatory cells, may exhibit as small lymphoid aggregates; 3 = severe inflammation: synovial intima five to seven or more cells thick, dense cellularity with inflammatory cells, containing many or large perivascular lymphoid aggregates. Bar = 100 μm.Back to article page