Four days after intraarticular injection, rats were killed, and deskinned right ankles were collected, embedded in Neg50 (Thermo Scientific, Waltham, MA) and frozen in liquid nitrogen. Frozen right ankles were scanned by µ-CT (viva-CT40, Scanco, Brütisellen, Switzerland). Three-dimensional reconstructions were segmented using the following parameters: sigma, 2.8; support, 2; threshold, 289. After µ-CT acquisition, fresh-frozen sections of the joints (10 µm in thickness) from the different groups were stained with H&E, and examined for the presence of infiltrates26.