Standardized methyl green-pyronin Y procedures using pure dyes

Fully standardized Methyl Green-Pyronin methods are presented. Pure Pyronin Y and purified Methyl Green or Ethyl Green are used either simultaneously in one dye bath or are used as a sequence of Pyronin Y and Ethyl or Methyl Green. Both methods, as shown by enzymatic pretreatment, give a reliable and reproducible staining in DNA with Ethyl or Methyl Green and of RNA with Pyronin Y on Carnoy fixed material. On formaldehyde fixed material it was found advantageous to use the sequential method as chromatin was hereby stained green instead of blue as seen with the simultaneous method.