Biological effects of dimethyloxaloylglycine. In control joints of STR/ORT mice, (a) immunohistochemical detection of type II collagen reveals homogeneous staining within the extracellular matrix apart from some irregularities due to degenerative changes in the superficial layers. (b) In contrast, administration of dimethyloxaloylglycine (DMOG) results in accumulation of type II collagen located intracellularly/pericellularly in the superficial layer. (c) Type II collagen-immunofluorescence of cultured nontreated primary chondrocytes typically displays a pericellular network of type II collagen fibers. (d) DMOG treatment of primary chondrocytes in monolayer culture leads to an intracellular retention of vesicle-like structures that stain positive for type II collagen. Expression of (e) phosphoglycerate kinase 1 (PGK1), (f) Sox9, (g) type II collagen α1-chain (Col2A1), (h) type I collagen α2-chain (Col1A2), (i) IL-1β and (j) IL-6 in cultured articular chondrocytes determined by real-time RT-PCR dependent on treatment with or without DMOG under 21% or 1% oxygen. Expression levels are shown as the mean ± standard deviation. *P <0.05, **P <0.01. Bar = 100 μm.