Late-stage articular cartilage degradation. Sections of 16-week normal Mig-6-flox (A, C) and Mig-6-flox;Prx1Cre conditional knockout (Mig-6-cko) knees (B, D) stained with Safranin-O and counterstained with Fast Green (tibia is at the bottom, femur is at the top; boxed areas in A, B are enlarged in C, D). At 16 weeks, the tibial articular cartilage of the Mig-6-cko knee is comparable in thickness to that of the normal knee (bars in C, D) but is discontinuous, with loss of surface integrity (* in D) and fusion with the overlying fibrogenic meniscal tissue (m). In addition, Mig-6-cko knee joints contain fused central ligaments which stain intensely with Safranin-O (lg in B), prominent osteophytes (op), and thin subchondral bone (sb). Scale Bar = 100 μm.
Shepard et al. Arthritis Research & Therapy 2013 15:R60 doi:10.1186/ar4233