<P> By far the most commonly used fixative in histology is formaldehyde . It is usually used as a 10 % neutral buffered formalin ( NBF ) , that is approx . 3.7 % - 4.0 % formaldehyde in phosphate - buffered saline . Because formaldehyde is a gas at room temperature , formalin - formaldehyde gas dissolved in water ( ~ 37 % w / v ) is used when making the former fixative . Paraformaldehyde is a polymerized form of formaldehyde , usually obtained as a fine white powder , which depolymerises back to formalin when heated . Formaldehyde fixes tissue by cross-linking the proteins , primarily the residues of the basic amino acid lysine . Its effects are reversible by excess water and it avoids formalin pigmentation . Other benefits include : Long term storage and good tissue penetration . It is particularly good for immunohistochemistry techniques . Also the formaldehyde vapor can be used as a fixative for cell smears . </P>
<P> By far the most commonly used fixative in histology is formaldehyde . It is usually used as a 10 % neutral buffered formalin ( NBF ) , that is approx . 3.7 % - 4.0 % formaldehyde in phosphate - buffered saline . Because formaldehyde is a gas at room temperature , formalin - formaldehyde gas dissolved in water ( ~ 37 % w / v ) is used when making the former fixative . Paraformaldehyde is a polymerized form of formaldehyde , usually obtained as a fine white powder , which depolymerises back to formalin when heated . Formaldehyde fixes tissue by cross-linking the proteins , primarily the residues of the basic amino acid lysine . Its effects are reversible by excess water and it avoids formalin pigmentation . Other benefits include : Long term storage and good tissue penetration . It is particularly good for immunohistochemistry techniques . Also the formaldehyde vapor can be used as a fixative for cell smears . </P>
commonly used as a preservative for tissue specimens
commonly used as a preservative for tissue specimens
formaldehyde
formaldehyde