The ability to view thick material using accelerating voltages higher than 100 KeV has greatly expanded the usefulness of electron microscopy. At or above 300 KeV, intact cultured cells and tissue sections as thick as 5µm can be visualized. However, under normal viewing conditions this increased depth produces confusing superposition of structures located at different planes along the Z axis. In order to separate spatial information in different planes, specialized procedures such as stereo pairs or animated tilt series have been employed. Although rapid, these procedures do not allow quantitation of parameters such as size, volume, or circumference. Computed Tomography produces a computer generated 3-D reconstruction from which quantitative data can be easily extracted.