Sample Preparation and Fixation for Histology and Pathology

The basic goal of all histological techniques is the identification of tissue components, both normal and pathologic. In the case of any immunodetection technique we expect: specific detection of the antigen with a mark strong enough to be easily detected; and a clear preservation of histological and cytological details of the environment. To achieve these expectations the technical procedures employed must be clearly understood so we can control the previous methodological steps, avoiding any failure and/or complication that could seriously affect the results of our study. In this chapter, we review the basic concepts related to representability of the sample, fixation process, and all procedures carried out before performing the immunohistochemical technique on paraffin sections, which constitute what we know as sample preparation. We describe and analyze the key events so the pathologist and/or the researcher can control the variables in order to obtain the best results in an immunodetection procedure.