The Cell Biology Core provides Program Project investigators and their supporting staff with technical support and consultation in cell culture development, preparation and experimental design, immunohistochemistry and ELISAs. The Core occupies dedicated laboratory space within the Division of Endocrinology and Bone and Mineral Diseases at the Jewish Hospital of St. Louis. The Cell Biology Core is responsible for the screening and purchasing of serum and the preparation of the various media required to prepare, culture and maintain the numerous cell lines carried in the main and media required to prepare, culture and maintain the numerous cell lines carried in the main and satellite laboratories and available for use by the investigators in each project of the Program to carry out their individual experimental protocols. Careful quality control measures have been taken to insure that media and sera are supportive of cell growth and continual attempts made to offer the investigators the "most appropriate, i.e. osteoblastic phenotype, and homogeneous cell" cultures. To continue pursuing the development of techniques and procedures which will ultimately satisfy the continued need for viable bone marrow, phenotypic rat and human osteoblasts and bone marrow stromal cells, and multiple cell lines of human and rodent origin, the basic organization of the Core has been expanded over that detailed in the previous renewal. In order to support and service the experimental protocols described in this application which are targeted to: 1) examine bone cell differentiation and communication via cell adhesion; 2) examine the regulation of osteoclast development and differentiation; 3) examine the regulation of cells differentiation by 1,25(OH)2D3; and 4) examine osteoclast-mediated bone remodeling, new technical support is proposed for the present renewal. To accomplish this goal, we plan new endeavors in the Cell Biology Core including technical support in the areas of: (1) immunohistochemical analysis of osteoblast development and osteoclast function; (2) analysis of cell culture supernatant for cytokines by ELISA; (3) providing services for the development, and preparation and/or maintenance of new cell lines, and 4) providing a centralized repository for cDNA probes. Based on current and projected usage, we expect that the Core resources will be extensively utilized and that demands for our services to grow during the next funding period.