(A) Osteon-like structures (black arrow) adjacent to residual cement. (B-C) Osteoclast-mediated resorption (double arrows) of NS-PTKUR in (B) 0C45S and (C) 45C0S. (D-F) Endochondral ossification in groups (D) 45C0S, (E) 0C45S, and (F) 10C35S evidenced by nodules of cartilage/chondrocytes (purple, #) and bone (*) embedded in NS-PTKUR. (Scale bar = 200 μm, single black arrow: osteon, double black arrows: osteoclast, #: cartilage/chondrocytes, *: cartilage undergoing mineralization.)