Two bovine models of osteogenesis imperfecta exhibit decreased apatite crystal size

In recent years advances have been made in detailing the changes in both collagen and noncollagenous proteins caused by a variety of mutations leading to osteogenesis imperfecta. Much less, however, is known about the mineral phase in the affected bone. In this report, we measured the crystallinity of the apatite in bovine OI bone. Line broadening of the 002 reflection (which estimates changes in the long or c axis of the crystals) and of the 310 reflection (which estimates changes in the thickness of the crystals) both show large decreases (30 and 35% respectively). Transmission electron micrograph measurements indicate that these changes were most probably a result of smaller crystals. No decrease in the ash weight of the bone was observed.