To analyses the effect of Cd on pro-inflammatory cytokine expression in collagen induced RA in joint tissues, immunohistochemical staining was carried out. Knee joints were removed and
fixed in 4% paraformaldehyde. After decalcification in 5% formic acid, 5 lm thick sections cut from paraformaldehyde-fixed, paraffin-embedded knee joints tissue blocks were mounted on
poly-l-lysine coated microscopic slides.