Formaldehyde fixation in the new millenium

This review deals with the general principles and problems of formaldehyde fixation. After a short description of 1) formaldehyde methods of productio n, 2) chemical properties of formaldehyde solution, and 3) kinetic of forma ldehyde binding in tissue, formaldehyde reactivity with the tissue biopolym ers, proteins and cucleic acids mainly, are described. Howformaldehyde fixa tion of tissues adversely affects the reactivity of cellular proteins with their respective specific antibody and the ways the most commonly used retr ieval techniques in oct ore, thereafter, discussed. Finally, concerns that need to be dealt with when formalin-fixed specimens are used for genomic an alysis and studies of DNA expression are highlighted.