Funds are requested through the Shared Instrumentation Grant Program of the DRR for purchase of a Scanning Electron Microscope. This instrument will replace a ten-year-old SEM and will be used and maintained by full-trained EM technicians in the Mayo Electron Microscopy Facility located in, and managed by the Department of Biochemistry and Molecular Biology. The SEM will serve several local users drawn from basic science and clinical departments. The principal users of, and users for, the SEM are described, but as an Institutional facility it is inevitable that the user base will be considerably broader than implied by those listed in this proposal. Mayo will continue to be responsible for all space, technician support, maintenance and supplies needed to sustain full operation of the instrument.