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Canine Osteon Formation (Modeling) and Remodeling During Development and Mechanical Loading
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The osteon (Haversian system) is the basic structural and functional unit of cortical bones in human and many other large mammals like dogs and cows. Different from mouse cortical bones consisting of uniform lamellar bones, osteons consist of multiple concentric lamellae surrounding a central vascular canal named Haversian canal. Osteon structures are significant for the function of skeletal system in providing both sufficient blood supply and mechanical support. Osteons also display striking changes under pathological conditions, such as osteoporosis. Despite their importance, there is limited research on osteons using large mammals, in contrast to the relatively exhaustive bone research using rodents. Therefore, there are many knowledge gaps in osteon biology, including the modeling and remodeling of osteons during early development and in response to mechanical loading. Here, by examining the cross sections of the tibia midshaft of young beagle dogs at postnatal day 1, day 14, day 28, and 4 months using different approaches, we demonstrated that periosteum had a major contribution to osteonal bone formation by giving rise to abundant “preosteon” structures – the unique semicircular canals that were highly cellular and would develop into future osteons. The endosteum, on the other hand, served as a location where bone resorption took place allowing the bone marrow cavity to enlarge. Furthermore, we investigated the effects of enhanced mechanical loading on the formation of new osteons and the remodeling of existing osteons by applying a novel loading model to the tibia midshafts of adult beagle dogs. Compared to the contralateral tibia without a loading device, the loaded tibia exhibited a preferential role of periosteum in new bone formation, with many details recapitulating the periosteal osteon formation process during early development. In addition, the remodeling activity of the existing bone area of loaded bone was also increased. In summary, our study was the first one to provide detailed information on the osteon modeling and remodeling during early development and under mechanical loading. Furthermore, this work lays a solid foundation for understanding the human bone responses under various physiological and pathological conditions, as well as in response to force-delivering medical devices.
Wang, Ke (2019). Canine Osteon Formation (Modeling) and Remodeling During Development and Mechanical Loading. Doctoral dissertation, Texas A&M University. Available electronically from