This is a Shared Instrument Grant request to purchase an electron microscope for a Research Core Electron Microscope Facility to be housed in the Department of Pathology of the Yale University School of Medicine. The facility will support at least eighteen investigators from the Departments of Pathology, Internal Medicine and Physiology. It will support two program projects, a liver research center grant and numerous individual grants from the National Institutes of Health as well as private funding agencies. The electron microscope chosen has the technical capabilities that suit the special needs of the projects which it will support.