What Is The Purpose Of Adding Methylene Blue To The Specimen

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pacorz | High School Teacher | (Level 3) Educator

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Methylene blue is a common lab stain and is used for many different types of cells. Methylene blue is an oxidizing chemical with a lot of biological activity; it does a very good job of staining DNA and RNA. It is believed that methylene blue actually bonds with the base guanine.

Because of its affinity for DNA and RNA, methylene blue will produce a darker stain in areas where those components are present. In the case of the human cheek cell, methylene blue causes the DNA in the nucleus to stand out so that the nucleus can clearly been seen in a light microscope. Since cheek cells have no pigmentation, without the dye there would be no contrast, which would make the cells hard to see and make it nearly impossible to view any internal details in them.