Many investigators at Yale University (Medical School and College) have a long-standing interest in the musculoskeletal disorders. These investigators represent numerous departments and disciplines. This interest in the pathophysiology of the skeleton has created a number of collaborative projects among interested investigators. As a result of those interactions investigators have been required to develop cell culture techniques within their own laboratories often leading to expensive duplication of already existing work. Although standard techniques are available, intra-laboratory variation in the quality and number of cells is unavoidable. Therefore, the Yale Core Center for Musculoskeletal Disorders will support a Cell Core. The main goal of the Cell Core is to facilitate the experimental use of authentic primary isolated mouse and rat osteoblastic cells as well as primary osteoclasts and osteoclast-like cells generated from co-culture. The Specific Aims of the proposal are to provide the following services: 1. Isolation and cultivation of primary murine and fetal rat calvarial osteoblasts. This will included large scale preparations for biochemical studies at RNA and DNA purification. 2. Cultivation of murine osteoclast-like cells generated from in vitro co-culture. 3. Isolation of authentic osteoclasts from rabbits and rats. 4. Training in the in vitro isolation and culture of osteoblastic and osteoclastic cells, so that investigators, appropriately trained, and maintain these cells in their laboratories.