Funds are requested under the DRR-BRS Shared Instrumentation Grant Program to purchase a JEOL Model JEM-100 CX Transmission Electron Microscope. This instrument is critically needed for the conduct of projects awarded by the Public Health Service to four major users and to two others for whom the use of ultrastructure will provide a new approach. Moreover, the electron microscope will be an asset for two additional investigators who are new faculty and have submitted grant applications to the Public Health Service. The Principal Investigators, although concentrated in the Department of Anatomy, include also faculty from the Departments of Pathology, Pediatrics and Pharmacology. The projects focus on the areas of neuroscience and musculoskeletal research, areas which have strengths in the Departments of Anatomy and Pathology, respectively. Thus, four of the five members of the Internal Advisory Committee have appointments in those Departments. The model of electron microscope requested has an established record of performance and is equipped with operational features ideal for a multi-user facility. The need for the equipment is critical since one of the two existing transmission electron microscopes in the College of Medicine (a Siemens 102 installed approximately 15 years ago) has become obsolete and is unusable. The remaining instrument, a Siemens 101, is of similar vintage and is currently the sole instrument used for both clinical and research needs. The combined clinical/research needs, in conjunction with a lack of dependability of this old instrument, severely impedes the progress of research already funded and ongoing, and discourages the initiation of other research requiring ultrastructure. The transmission electron microscope for which funds are requested will be dedicated solely to research, and its acquisition will: 1) buttress significantly several PHS-funded research projects; 2) nurture future new research projects and the extension of current projects to encompass ultrastructural investigations, and 3) augment the recent institutional purchase of a computer aided image analysis system.