POLYCHROMED METHYLENE BLUE

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We have talked in detail about Romanowsky/Malachowski stains in my previous posts.

 I hope its now clear that the so called Romanowsky effect is because of polychromed methylene blue.

In this post, lets see in detail what polychromed methylene blue is.

Poly- chromed

Prefix ‘Poly’ is derived from greek word, which means ‘many’ and ‘Chrome’, comes from the greek word- chrom, which means colour. So, in simple terms, polychromed means many colours.

Methylene blue when used in pure form did not produce many colours. It produced multiple colours along with the characteristic purple hue only when the methylene blue used was aged.

In Romanowksy type stains, eosin Y is combined with polychrome methylene blue or azure B.

Methylene blue when subject to oxidative demethylation, results in the breakdown of methylene blue into multiple other stains, some of which produce subtle variations in colour. This is known as polychromed methylene blue.  It may contain upto 11 dyes, including methylene blue, azure B, azure C, thionine, methylene violet Bernthesen, methyl thionoline and thionoline. The exact composition depends on the method used and even batches of the stain from the same manufacturer may vary in composition.

Azure B also produces the Romanowsky effect. The original source of azure B is one of the oxidation products of methylene blue, treated with oxidizing agents or allowed to age naturally.

This is the story of the magical purple hue which we see in our blood smears everyday.

References:

1.     Romanowksy stains. Wikiwand.com

                                                                                          Written by Dr.Priyavadhana B


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