The analysis of frozen tissue by antibodies can be accomplished by the quick freezing of a small tissue sample in liquid nitrogen. Super-cooled isopentane can also be used to further the preservation process. Freezing preserves the available proteins in a near-native state for their identification by antibodies raised against naturally folded proteins. The tissues are sectioned onto charged glass slides where they can be optimally fixed in weakly or non-denaturing solutions such as acetone or those that are alcohol-based. Following mild pretreatment steps to allow for antibody use with low background, (the endogenous peroxidase enzyme or oxidative compounds quenched in a hydrogen peroxide solution and available charged sites blocked by incubation in a normal serum solution) the sections are ready for antigen detection.