Romanowskytype

Romanowsky-type stains are a family of polychromatic staining methods used to visualize cells in blood smears, bone marrow, and cytology specimens. Named after the Russian physician Dmitri L. Romanowsky (1861–1921), these stains rely on a mixture of basic azure dyes and acidic eosin to differentially color cellular components. The best-known members of this group are Wright stain, Giemsa stain, May-Grünwald stain, and the combined May-Grünwald–Giemsa (MGG) stain. These formulations are widely used in clinical laboratories worldwide for routine hematology and cytology work.

Principle and appearance: In Romanowsky-type staining, fixed smears are exposed to a stain solution containing eosin and azure dyes. Nuclei and basophilic structures take on blue to purple hues, while cytoplasm and eosinophilic granules become pink to orange. Granules in granulocytes and other cell features are highlighted, enabling discrimination of myeloid, lymphoid, and other cell types. The exact color tone depends on the specific formulation and pH, but the general pattern of differential staining is consistent across variants.

Applications and considerations: The stains are standard for evaluating blood films, bone marrow aspirates, and various cytology specimens, including malaria, parasites, and inflammatory cells. They support diagnosis of hematologic disorders such as anemia, leukemias, and myelodysplasia by morphology. Staining quality relies on proper fixation, reagent composition, and pH; variations can affect color balance and contrast, making standardization and quality control important.