For cell organelles not visible with light microscopy/H&E stain. Examine the cells ultrastructure. Effective magnification of 100,000 X
Preparation: fixed, dehydrated, embedded in plastic, setioned, placed on EM grids, and contrast with staining with lead and uranium salts
Imaging: electrons pass through the sample. Electron dense areas appear dark on fluorescent screen of the elctron microscope or dark region on film
Diagnostic Pathology: Diagnosis kidney disorders, tumors, identification of infectious agents e.g. viruses.