The primary aim of tissue fixation is to preserve tissue in the long term, ideally without causing alterations in morphology or biochemical integrity. Optimal fixation should therefore inhibit autolysis while preserving enzyme activity and antigen reactivity. However, some of these requirements are mutually exclusive. For example, to stop autolysis, proteolytic enzymes must be inhibited (1 ). At present, it is not possible to find a fixation technique that fulfils all of these criteria.