The Department of Pathology Electron Microscopy Laboratory performs ultrastructural studies on tissues by transmission electron microscopy (TEM). TEM has much higher resolution than light microscopy and can allow visualization of cellular organelles, intercellular junctions, and extracellular proteins. It can clarify architectural details that aid in the diagnosis of glomerular, neurological, muscular and cutaneous diseases. TEM specimens are received in a specialized fixative and are processed by hand for embedding in a plastic medium. The plastic blocks are sectioned at 0.5 micron and stained with toluidine blue to identify tissues that may be informative. The region of interest is further narrowed and thin sections are prepared for examination in the electron microscope. The thin sections are approximately 0.1 microns (100 nanometers) in thickness and are stained with uranyl acetate and lead citrate. These metal ions bind to the tissues and block the transmission of the electron beam in the microscope. The resulting images are captured with digital cameras and evaluated for diagnostic abnormalities that support or refute the diagnosis obtained by light microscopic examination.