The methyl green-pyronin method

It has been shown that when methyl green is used to stain DNA, as by Kurnick's method, it binds firmly and cannot be washed off by immersion in a buffer solution. When tissue is stained with methyl green for a short time, however, either alone or mixed with pyronin, no strong binding is produced between the methyl green and the DNA. It is suggested that although Kurnick's method may be selective for DNA, the differential staining of cell structures produced by short treatment with methyl green-pyronin is due to competition.