|
Fixation |
Mechanism |
Advantages/Disadvantages |
Examples |
|
Acetone |
Precipitation |
Excellent preservative of immnuoreactive sites, poor penetrator. Used only for cells and sections. May cause protein loss, shrinkage and artifacts.
|
100% acetone (4 or –20 ˚C) |
|
Ethanol |
Precipitation |
Good antibody penetration, don't block immunoreactive site. Conformational change may occur. Preferred for preserve DNA and RNA. May cause protein loss, shrinkage and artifacts.
|
70% cold ethanol |
|
Methanol |
Precipitation |
100% methanol (-20 ˚C) |
|
Glutaraldehyde |
Cross-linking |
Glutaraldehyde provides the best morphological preservation but causes high background fluorescence. Difficult for macromolecules to penetrate. Cross-links DNA and RNA.
|
0.4% Glutaraldehyde, 4% Paraformaldehyde, 0.1 M Phosphate buffer, pH 7.4 |
|
Formaldehyde |
Cross-linking |
Well tolerated by tissue and have good penetration. Cross-linking slower than Glutaraldehyde. Optimal fixation condition variable. Difficult for macromolecules to penetrate. Cross-links DNA and RNA. |
10% formaline or 1-5% formaldehyde in PBS
Neutral buffered formalin
Bouin’s solution (0.9% picric acid,5% acetic acid, 1% formaldehyde)
Zinc chloride (2.5%ZnCl2,6%formaldehye,0.95%acetic acid)
|
