are floated on top of a liquid as they are cut and are carefully picked up onto grids suitable for TEM specimen viewing. The thickness of the section can be estimated by the thin-film interference colors of reflected light that are seen as a result of the extremely low sample thickness. Vibrating The vibrating microtome operates by cutting using a vibrating blade, allowing the resultant cut to be made with less pressure than would be required for a stationary blade. The vibrating microtome is usually used for difficult biological samples. The cut thickness is usually around 30–500 μm for live tissue and 10–500 μm for fixed tissue. A variation on the vibrating microtome is the Compresstome microtome. The Compresstome uses a specimen syringe or "lipstick-like" tube to hold the tissue. The tissue specimen is completely embedded in agarose (a polysaccharide), and the tissue is slowly and gently pressed out of the tube for the vibrating blade to cut. The device operates in the following way: the end of the specimen tube where the tissue emerges is slightly narrower than the loading end, which allows gentle "compression" of the tissue as it comes out of the tube. The slight compression prevents shearing, uneven cutting, and vibration artifacts from forming. Note that the compression technology does not damage or affect the tissue being sectioned. There are several advantages of the Compresstome microtome: 1) the agarose embedding provides stability to the entire specimen on all sides, which prevents uneven slicing or shearing of tissue; 2) the compression technology gently compresses tissue for even cutting, so that the blade doesn't push against the tissue; 3) faster sectioning than most vibrating microtomes; and 4) it cuts tissue from older or more mature animals well to provide healthier tissues. Saw The saw microtome is especially for hard materials such as teeth or bones. The microtome of this type has a recessed rotating saw, which slices through the sample. The minimal cut thickness is approximately 30 μm and can be made for comparatively large samples. Laser The laser microtome is an instrument for contact-free slicing. Prior preparation of the sample through embedding, freezing or chemical fixation is not required, thereby minimizing the artifacts from preparation methods. Alternately this design of microtome can also be used for very hard materials, such as bones or teeth, as well as some ceramics. Dependent upon the properties of the sample material,