Large electron microscopes utilize lasers to magnify objects. These require cooling mechanisms to prevent overheating. There are many types of electron microscopes used today. However, (SEM) scanning electron microscopes and (TEM) transmission electron microscopes are used specifically in the medical field. Primarily for use in the field of pathology. Pathology is the study of cause and effect of disease on humans, plants, and animals. Electron microscopes are extremely effective for viewing structures in individual cells. Pathologists are able to create new histochemical techniques to stain and identify specific structures of cells and bacteria. This is especially important for diagnosing tumors that are hard to identify and treat. Cytogenetics and gene rearrangement have also benefited from the electron microscope viewing capacity. Diagnosing and treating renal disease, cancers, kidney disease, and identification of infectious microorganisms are just a few of the areas where electron microscopy has proven extremely valuable. Microscopes on this scale on not found in regular hospital settings. This type of medical equipment is costly and is used in large research and development facilities.