The goal of the DERC Electron Microscopy (EM) Core Facility is to provide complete, first-rate EM service to DERC researchers at UMMS. The Facility is centrally located in a newly renovated suite in the basement of the Basic and Clinical Sciences Building. It is directed by Drs. George Witman and Roger Craig, and managed on a day-to-day basis by Dr. Gregory Hendricks, a full-time professional electron microscopist with extensive experience in virtually all EM methods. Equipment includes Philips CM120, CM12 and CM10 transmission electron microscopes and an ETEC Autoscan scanning electron microscope, a Balzers BAF400T freeze-etching system;three Reichert Ultracut E cryo-ultramicrotomes, and other equipment for specimen preparation. Techniques include immuno-EM, cryo-EM, and preparation of specimens by conventional thin sectioning, negative staining, metal shadowing, cryoultramicrotomy, rapid freezing, freeze substitution, freeze-fracture/freeze-etch, and critical point drying. Dr. Hendricks, aided by an assistant, can provide all services from specimen preparation to printing of electron micrographs. Alternatively, investigators may use Facility reagents and equipment to carry out their own specimen preparation and examination, with assistance from Facility staff as needed. Consequently, the Facility works just as well for users with no EM experience as for those with considerable EM experience. By centralizing all aspects of EM in this facility, the DERC provides its members with the best possible EM services in the most cost- and time-effective manner. The Facility, which is open to all UMMS researchers, is supported by a combination of institutional funds and user chargebacks;DERC investigators are charged at one-half the rate for non-affiliated UMMS researchers. Many DERC members use EM as an integral part of their research, and DERC members have published numerous papers that report results obtained in the EM Core Facility.