The objective of this proposal is to purchase an in vivo, three-dimensional micro-computed tomography imaging system. This system has the capability of digitizing the three-dimensional morphology and microarchitecture of anatomic structures in vivo, at resolutions up to 9 micron isotropic voxel size. This system will essentiall replace a system that has been part of a Core facility operation at the University of Michigan for the past eight years, but will no longer be supported by the vendor, and no longer supports the high resolution needs of investigators at the institution. Our Core facility houses both in vivo an ex vivo microCT imaging systems which span in vitro sub-micron voxel size to 45 micron in vivo imaging. The principal rational for the purchase of this new system is based on the needs of a large group of well-funded investigators which now requires more refined in vivo resolution, lower radiation doses, and further scan control including cardiac and respiratory gating to facilitate ongoing and new investigations. The data that can be acquired with the in vivo micro-computed tomography system enables investigators to study mechanisms associated with skeletal diseases, growth and development, aging and fragility, regenerative medicine strategies, cancer and metastatic tumor invasion, diabetes, metabolic disease, and osteoarthritis. Additionally, the system offers the ability to perform ex vivo high resolution imaging on objects that cannot fit into our current ex vivo systems, such as large anatomic specimens and archaeological artifacts including mummified animals.