A high resolution Zeiss EM-10 transmission electron microscope (TEM) is being requested as a replacement for the existing fourteen year old AEI Corinth 275 TEM in the School of Public Health's Toxicology Electron Microscopy Laboratory. Although the current instrument has served most of our needs in the past, it is outdated and has been causing the laboratory an increased number of problems related to service, replacement parts, and poor or inadequate performance-all of which reduce efficiency and productivity in the laboratory. A high resolution TEM is essential for some of the projects described in this proposal and would be highly beneficial for all of the others. This instrument will be especially advantageous for the currently funded NIH and related projects on cutaneous carcinogenesis and predictive cutaneous toxicology. The projects for which this instrument is needed can be grouped into eight areas of study. These areas are: 1) epidermal carcinogenesis, 2) predictive cutaneous toxicology, 3) the development of a percutaneous energy transmission device, 4) the localization of neurotoxic esterase, 5) the development of an animal model for Reye's syndrome, 6) characterization of influenza viruses used in vaccines, 7) the ultrastructural and immunocytochemical characterization of lymphocyte sub-populations of patients with diabetes mellitus, 8) vaccine parameters for schistosomiasis.