Figure 5From: Animal model of acute gout reproduces the inflammatory and ultrasonographic joint changes of human gout Standard light and compensated polarized light microscopic analysis of synovial fluid (SF) from the monosodium urate (MSU) and allopurinol groups. Observe the presence of intra- (arrows) and extra-cellular negatively birefringent needle-shaped crystals in the MSU-crystal group at day 1. MSU crystals phagocytized by polymorphonuclear cells were seen at days 1 and 3. Absence of MSU and allopurinol crystals was observed at day 7.Back to article page