Equis ISSN 2398-2977

Staining techniques: Romanowsky stains - overview

Contributor(s): Annalisa Barrelet, Kathleen P Freeman, Karen L Gerber, T Scrivener, Malcolm J Wheeler


  • Romanowsky stains are neutral stains composed of a mixture of oxidized methylene blue (azure) dyes and Eosin Y.
  • The azures are basic dyes that bind acid nuclei and result in a blue to purple color.
  • The acid dye, eosin, is attracted to the alkaline cytoplasm, producing red coloration.


  • Blood films, bone marrow examination, cytology.


  • Readily available, easy to prepare, maintain and use.


  • technique:
    • Nuclear and nucleolar detail not as good as papanicolaou, but adequate to distinguish neoplasia from inflammation.
    • Ph-sensitive therefore buffer and rinse water are critical (refer to artifacts/errors).


Work time

  • Preparation: depends on type of Romanowsky stain - refer to sub-categories.


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Further Reading


Refereed papers

Other sources of information

  • Harvey J W (2001) Blood and Bone Marrow of Domestic Animals. In: Atlas of Veterinary Hematology. W B Saunders. pp 11.
  • Dacie J V Sir & Lewis S M (2001) Practical Hematology. 9th edn. W B Saunders Co. ISBN 0-4430-6377 X.
  • Pratt P W (1997) Laboratory Procedures For Veternary Technicians. 3rd edn. Mosby. pp 547.
  • Bain B J (1989) Blood Cells - A Practical Guide. Gower Medical Publishing. pp 8-10.
  • Hall R & Malia R (1984) Medical Laboratory Hematology. Butterworth & Co Ltd. pp 132-136.