To examine the tissue components, it is necessary to process the tissue in a number of ways. First, to prevent decomposition, tissue is usually subjected to fixation . Finally, to allow us to see the structures, the tissue is subjected to a variety of visualization techniques. These techniques will be detailed below.
Fixation involves processing the tissue to preserve the structure of the tissue.
It is usually, but not always, done before sectioning. During fixation, cell metabolism is stopped. Formaldhyde reacts with the amino groups of proteins, and thus preserves the general structure of the cell and extracellular components . One means of accomplishing this is called cryosectioning- tissue can be frozen and sectioned at a low temperature, using a cryostat with a razor blade knife. During this process, the holder also moves up and down, which brings the edge of the tissue down on the top of the blade.