Laidlaw's Trichrome
for Inclusion Bodies


Weigert's iron hematoxylin or equivalent
Solution A
Acid fuchsin 1 g
Distilled water 100 mL
Solution B
Phosphomolybdic acid 1 g
Distilled water 100 mL
Solution C
Orange G 0.25 g
Ethanol, 100% 70 mL
Distilled water 30 mL

Tissue sample
3µ paraffin sections of tissue fixed in Laidlaw's own fixative is specified. This is an acidified mercuric chloride solution and other, similar, mercuric chloride fixatives would likely be acceptable. Other fixatives may be acceptable, but this should be established by trial with known positive materials.


  1. Bring sections to water via xylene and ethanol.
  2. Stain nuclei with Weigert's iron hematoxylin or equivalent.
  3. Place into solution A for 5-15 minute.
  4. Rinse with distilled water.
  5. Place into solution B for 30 seconds.
  6. Rinse quickly with distilled water.
  7. Place into solution C until inclusion bodies are differentiated.
  8. Dehydrate with ethanol.
  9. Clear with xylene and mount with a resinous medium.

Expected results


  1. Clearing with benzene was specified. This solvent is no longer used due to its toxicity. Xylene or toluene should be satisfactory.
  2. Laidlaw's fixative contains:–
    Water 250 mL
    Mercuric chloride 10 g
    Acetic acid, glacial 12.5 mL



Gray, Peter. (1954)
The Microtomist's Formulary and Guide.
Originally published by:– The Blakiston Co.
Republished by:– Robert E. Krieger Publishing Co.
    Pappenheimer and Hawthorne, (1936)
    American Journal of Pathology, v. 12, pp.627




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