Post Osmication

The process of post osmication is to preserve lipids so that they may be seen in paraffin sections. Unlike post chromation, post osmication allows the demonstration of all lipids, including triglycerides. Staining is usually unnecessary as the post osmication procedure itself blackens lipids, and they will appear darkly coloured in unstained paraffin sections. Many dyes stain poorly following osmium treatment.


Osmium tetroxide is very expensive, so I suggest that 0.1 gram sealed vials be purchased for single occasion use and the contents of one vial dissolved in 20 mL distilled water. The chemical must be dissolved in distilled water as it is very susceptible to reduction. It is safest if triple distilled water is used but that is not absolutely necessary. Unused solution may be kept for a short while if light is excluded, but any form of contamination will cause reduction and render it useless.

Osmium tetroxide gives off fumes which cause a piercing headache. Avoid inhaling these fumes. Make the solution in a fume chamber which is turned on and extracting properly. Carry out the procedure under the fume chamber until the final wash. Dispose of the used osmium tetroxide solution and washings according to local regulations.


No specific reference.




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