Periodic Acid

Fluorescent Schiff


Periodic acid solution
Fluorescent Schiff reagent

Tissue sample
5µ paraffin sections of neutral buffered formalin fixed tissue are suitable.
Other fixatives are likely to be satisfactory.


  1. Dewax and hydrate sections.
  2. Place in periodic acid for 10 minutes.
  3. Wash well with tap water.
  4. Rinse with distilled water.
  5. Place in fluorescent Schiff reagent for 20 minutes.
  6. Wash well with tap water.
  7. Place in acid alcohol, two changes, 5 minutes each.
  8. Wash well with tap water.
  9. Dehydrate, clear and mount in a non fluorescent resinous medium.

Expected results
Using a BG 12 exciter filter, and OG 4 (yellow) and/or OG5 (orange) barrier filter,
1-2-glycols fluoresce yellow with acriflavine and green-red with acridine orange.
Periodic acid fluorescent Schiff


  1. The same materials fluoresce as would be red or pink in a regular PAS reaction.
  2. If background fluorescence is too bright it may be quenched with alum hematoxylin for 1 minute, or 0.5% aqueous potassium permanganate for 1 minute. Quench immediately before the final dehydration step. This should be done with caution as it may reduce fluorescence.



Culling C.F.A., (1974)
Handbook of histopathological and histochemical techniques Ed. 3
Butterworth, London, UK.




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