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. Author manuscript; available in PMC: 2017 May 1.
Published in final edited form as: Matrix Biol. 2016 Mar 3;52-54:339–354. doi: 10.1016/j.matbio.2016.03.001

Figure 1. Abnormal cartilage, osteophytes and bone forming in Prg4−/− mice.

Figure 1

Frontal sections from TMJs prepared from 3 month- (A, C), 6 month- (D) and 12 month-old (B, E–H) control (A, B) and Prg4−/− (C–H) mice were processed for Hematoxylin (A–C, E, G) or Safranin-O/fast green (D, F, H) staining. Multiple osteophytes (D, E, F; double arrowhead) with preferential growth into the upper joint cavity (ujc) in Prg4−/− mice resulted in the increased roof of the GF thickness (rgf, bracket) and decreased the space of the upper joint cavity (B vs E, G). Note that osteophyte formation was initiated in 2 distinct sites of the GF/eminence: the articulating surface (double arrowhead in D–F) and the synovium/articular cartilage junction (arrowhead in E, F). Note also that bone tissue forming in the posterior portion of Prg4−/− TMJ was supplied with well-developed nutrient vessels (arrowheads) and coated with periosteum-like tissue (H; po, bracket) (H). 3D microCT images of mandibular condyles from 12 month-old control (I–O) and Prg4−/− (J–P) mice: sagittal (I, J), bird’s eye (K, L) or frontal (M, N) view (n=3 for each group). X-ray images of articular discs from 12 month-old control (O) and Prg4−/− (P) mice and ectopic mineralization detected in mutant disc (P; arrowheads). Analysis of serial frontal and parasagittal sections reveals: increased incidence of ectopic cartilage/osteophyte formation in GF, disc and condyle in Prg4−/− mice (Q. n=5 for 3 months and 5 months and n=3 for 12 months); fold change of Safranin-O stained area of articular cartilage and osteophytes of glenoid fossa/section (R, n=3 for mouse/each group); and thickness of roof of glenoid fossa (rgf) (S, indicated by bracket, n=3 for mouse/each group) in Prg4−/− mice compared to age-matched control littermates. Areas were randomly selected from 8 sections per sample (n=3 for mouse/each group, *p <0.05, **p <0.01) and presented as average ±SD. Scale bars: 0.9 mm in A for A, B, C, E, G; 550 μm in D for D, F; 65 μm in H; 1.2 mm for I–P. gf, glenoid fossa; dc, disc; cd, condyle, ujc, upper joint cavity; po, periosteum; lpm, lateral pterygoid muscle.