Mowry's Colloidal Iron
for Acid Mucosubstances


Acetic acid, glacial
Potassium ferrocyanide, 2% aqueous
Hydrochloric acid, 2% aqueous
Müller's Colloidal iron suspension
Working colloidal iron
Distilled water 15 mL
Acetic acid, glacial 5 mL
Colloidal iron suspension 20 mL
pH should be 1.1 - 1.3
Perls' solution
2% potassium ferrocyanide 1 vol
2% hydrochloric acid 1 vol

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


  1. Bring sections to water via xylene and ethanol.
  2. Rinse with 12% acetic acid for 30 seconds.
  3. Place in freshly made working colloidal iron for 1 hour.
  4. Rinse with 12% acetic acid, 4 changes of 3 minutes each.
  5. Place into freshly made Perls' solution for 20 minutes.
  6. Wash in running tap water for 5 minutes.
  7. Counterstain with Feulgen, PAS or a strictly progressive Hemalum.
  8. Optionally, dip in aqueous picric acid, then rinse with tap water a few seconds.
  9. Dehydrate with ethanols.
  10. Clear with xylene and mount with a resinous medium.

Expected results


  1. Step 7 could be replaced with a simple counterstain, such as neutral red or nuclear fast red.
  2. Although a PAS will allow neutral mucosubstances to be demonstrated red in contrast to the blue of acid mucosubstances, the two are often mixed and the distinction may not be clear.


Humason, G. L., (1967)
Animal tissue techniques, Ed. 2
W. H. Freeman and Company, San Francisco, Ca, USA




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