What is the principle behind tissue fixation?
"Fixation" is a process of stabilization important for anatomical study of biological tissue. To achieve this goal, one must arrest the decomposition caused by tissue enzymes and decay; it is usually desirable also to harden the tissue for convenient handling. The two basic approaches involve physical methods (rapid heating or quick-freezing) and/or chemical methods. Nearly all chemical methods were originally developed for the leather tanning industry, which faces similar problems.
The most widely-used chemical fixative is 4% formaldehyde gas dissolved in water or buffer. This (moderately toxic) agent rapidly penetrates tissue and (more slowly) denatures proteins, arresting enzymatic degradation. It also cross-links proteins, leading to tissue hardening. Glutaraldehyde, a di-aldehyde which cross-links very effectively, is often used for electron microscopy. A wide range of other chemical fixatives are sometimes used, including organic chemicals like tannic acid, picric acid, and absolute alcohol, and (highly toxic) inorganic fixatives like potassium dichromate, mercuric chloride, and osmium tetroxide. Their mechanisms of action are poorly-understood, but generally involve denaturation of protein.
What is an example fixation?
Fixation (obsession, compulsion, unhealthy preoccupation): He was doing fine until he developed this fixation with food colors; now he'll only eat food that is colored red. Fixation (histology): The laboratory staff are working on fixation of the latest batch of tissue samples. Fixation (developmental halt): Her fixation is currently at the three-year-old stage. Fixation (fastening in position): If we can achieve fixation of the support beams in their current orientation, the roof will remain stable…
What is formalin fixed paraffin embedded tissues in tissue processing?
A formaline fixed parrafin embedded tissue is a piece of tissue which is first separated from a specimen animal by disection or biopsy. Then, this tissue is fixed in order to prevent it from decaying or degeneration and to examine it clearly under a microscope for histological, pathological or cytological studies. This fixed tissue is then embedded in the wax to cut its fine sections and then, to stain it with Hemotoxylin and Eosin Stain…