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Index >> Staining Methods in Microbiology >>Romanowsky Stains

Romanowsky Stains

	Romanowsky stains These stains are very useful for the demonstration of spirochetes, staining of erythrocytes, malarial parasites in blood smears, and other parasites. The original Romanowsky stain was made by dissolving compound made by mixing eosin and zink free methylene blue. The original composition of stain has now been modified considerably which gives better results and is easier in preparation and use. Under this heading, May-Grundwald, Leishman, Wright and Giemsa’s stains are included.
Their usefulness lies in their ability to produce a range of shads between blue and red. They impart a reddish purple colour to the chromatin of malarial and other parasites. This colour is due to the oxidation products like azures which are formed when methylene blue is ripened either by aging or by heating with sodium carbonate. The ripened methylene blue is mixed with water soluble eosin which results into formation of precipitates. These precipitates are dried and dissolved in alcohol at pH 6.5
Each modification of Romanowsky’s stain differs in the ripening or oxidation process and relative proportion of methylene blue and eosin. Romanowsky stains are diluted for staining purpose with distilled water. It is important that the distilled water used for dilution should be at neutral pH. Slight alteration in the pH may alter significantly the colour of granules in W.B.C. etc. and will result into false conclusion. Therefore, the best is to use buffer solution instead of distilled water or distilled water should be buffered to control pH. With old films the staining may be excessively blue. Good differentiation may be obtained by washing briefly with 1% sodium dihydrogen orthophosphate solution prior to staining.

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