It is well known that biopsy, surgical and postmortem tissues fixed in formaiin and embedded in paraffin require antigen retrieval for diagnostic pathology. Various methods, including heating, enzymatic digestion, ultrasonication, and detergents, are in use for achieving antigen retrieval. A combination of these methods is also employed. However, the most effective methodology for antigen retrieval in a wide variety of tissues involves heating at high temperature using a microwave oven, an autoclave, a pressure cooker, or a hot plate. Among these treatments, heating the tissue sections (4 urn thick) in 0.01 M sodium citrate buffer (pH 6.0) in a microwave oven is the most widely used technique for antigen retrieval. To obtain efficient and reproducible antigen retrieval, the microwave oven must be used carefully and optimally. The following steps are recommended to achieve these goals (Hayat, 2000 a, b).

The causes of most hazards encountered in using a microwave oven are straight forward and can be avoided by taking necessary precautions. Higher power settings and longer durations of heating than optimal for a given study should be avoided. Because overheating is not uncommon, the time setting should be checked.