FIGURE 7.

OPN expression in osteoarticular lesions in WT and Hyp mice. (A) WT calcaneal enthesis showed a strong OPN expression at tidemark (red arrows) between uncalcified and calcified fibrocartilage compared to Hyp mice at M12. Cellular expansion of mineralizing fibrochondrocytes of both Achilles tendon and plantar fascia ligament insertions into the calcaneal tuberosity showed faint OPN expression in Hyp mice. pf, plantar fascia ligament; at, Achilles tendon; mt, mineralized fibrochondrocytes of Achilles tendon; mp, mineralized fibrochondrocytes of plantar fascia ligament; c, calcaneal tuberosity; t, tendon (scale bars, 100 μm). (B) OPN immunostaining in Hyp mice showed a strong expression in sacroiliac joint compared to that in WT mice at M3. The staining was associated with the mineralized matrix rather than the enlarged osteoid matrix (red arrowheads) (scale bars, 200 μm).