ISSN 2398-2969      

Staining technique: Romanowsky stains - overview


Synonym(s): Romanowsky


  • The choice of stain used is dependent on availability of equipment and staining solution in practice, the experience and preference of the clinician.
  • Stains can be either applied manually with the aid of cuvettes, or mechanically in automated staining systems.
  • Romanowsky stains are neutral stains composed of a mixture of oxidized methylene blue (azure) dyes and eosin Y.
  • Romanowsky staining is the prototypical cytological staining method. Changes in the methodology have lead to the evolution of other linked staining methods.
  • Romanowsky stains include Wright's, Giemsa, Wright-Giemsa, May-Grunwald-Giemsa and Diff-Quik.
  • Buffer is essential to enable the dyes to precipitate out of the solution and bind to sample material.
  • The azures are basic dyes that bind acid nuclei and result in a blue to purple color.
  • The eosines are acidic dyes that are attracted to the alkaline cytoplasm, producing red coloration.
  • They generally provide excellent nuclear detail and also clear differentiation of the cytoplasm.
  • The alcohol based 'fast' staining kits such as Diff-Quik are readily available and commonly used in practice.


  • Bone marrow examination.
  • Blood films.
  • Cytology.
  • Stain cells to identify abnormalities in morphology and pathological changes.


  • Easy to prepare.
  • Readily available.


  • Nuclear and nucleolar detail not as defined as Papanicolaou stain. Is adequate to distinguish neoplasia from inflammation.
  • pH sensitive - buffer essential.
  • Can get variation in coloration with a change in staining times and pH.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Cray C & Zaias J (2004) Laboratory procedures. Vet Clin Exotic Anim Pract (2), 487-518 PubMed.

Other sources of information

  • Merck KGaA (2013) Cytodiagnosis Staining Methods. Merck Millipore Manual.
  • Dunn J K & Gerber K (2005) Diagnostic Cytology. In:BSAVA Clinical and Feline Clinical Pathology. 2nd edn. Eds: Villiers E & Blackwood L. BSAVA, Gloucester. pp 305-339.
  • Dacia Sir J V & Lewis S M (2001) Practical Haematology. 6th edn. Longman Singapore Publishers Pte Ltd. pp 50-61.


  • Mary Pinborough, Pinmoore Animal Laboratory Services Ltd, The Coach House, Town House Barn, Clotton, Cheshire CW6 0EG, UK. Tel: +44 (0)1829 781855; Email: ; Website: .

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