Methyl green has been used in the histological staining of ovaries. It has also been used as a counterstain in various cells.
Marker dye for DNA in acid and neutral media.
Methyl green is mainly used as a DNA stain in histochemistry. At low concentrations it binds selectively to AT-rich regions of native DNA. However, at high concentrations it is present at all available DNA sites. 
Material may be a mixture of monobromo-monochloro and dichloro ZnCl2 salts.