what is fixation in histopathology

Fixation in histopathology is the process of preserving biological tissues from decay due to autolysis or putrefaction. The main objective of tissue fixation is to preserve cells and tissue components in a "life-like state" and to do this in such a way as to allow for the preparation of thin, stained sections. Fixation is a critical step in the preparation of histological sections, and it is the foundation step behind the study of pathology. The process of fixation aims to prevent or arrest the degenerative processes that commence as soon as a tissue is deprived of its blood supply. Fixation terminates any ongoing biochemical reactions and may also increase the treated tissues mechanical strength or stability. The fixation step is the single most critical factor in all the histopathological procedures. Fixation can be achieved through different methods such as heat fixation, perfusion fixation, and immersion fixation. An ideal fixative should preserve the tissue sample in a state as near to life as possible, and the choice of fixative and fixation process ultimately depends on what one wants to accomplish.