Histological evaluation of joint architecture
At the end of the 10-day period of monitoring, the hind feet of the mice were fixed in 10% buffered formalin solution, decalcified (Rapid-Cal™; BBC Biochemical, Dallas, TX, USA), embedded in paraffin wax positioned laterally and sagittally sectioned. Serial sections of 5 to 6 μm thickness were obtained, dewaxed and stained with H & E or toluidine blue.
The stained sections were scored for changes to joint architecture by an observer blinded to the study groups. Each section was screened for changes to the joint architecture, and every joint was scored as follows: normal; mild (minimal synovitis, some cartilage loss, shrinkage in the size of cartilage chondrocytes with denucleation, and bone erosions limited to discrete foci); moderate (more extensive synovial hyperplasia, destruction of large segments of the cartilage and considerable bone erosions caused by an invasive pannus front); and severe (complete destruction of the joint architecture).