Methylene Blue is a popular alkaline stain used to view microscopic life in brilliant color. It helps make cells show up against their background, where their shape can help you determine what they are (their morphology).
It's attraction to acid makes it particularly useful for viewing animal cells since these cell nuclei contain deoxyribonucleic acid (DNA). It’s also used in aquariums to guard against fungal infections in fish.
Eosin Y Stain is a reversible, fluorescent red, acidic dye, commonly used in hospital histology labs. Eosin's most important medical uses are in blood and bone-marrow testing, including the PAP smear. It can also test for protein in plant, animal and blood specimens. This stain is a valid substitute for Congo Red or Neutral Red and is frequently used as a counter-stain to Haematoxylin in H&E staining.Both employ the same process, as follows.
Prepare a wet mount slide with a specimen.
Place a single drop of stain on one outer edge of the cover slip on top of your slide.
Place some paper towel against the opposite edge of the cover slip - as close to the edge as possible.
The paper towel will draw the stain underneath the cover slip.
Wait until all of the stain has been pulled in between the cover slip and the slide.
The stain should completely cover the specimen on the slide.
If it does not, add another drop of stain to the edge of the cover slip.
Remove the piece of paper towel and place the slide on the microscope stage and you should see cell nuclei show up as the darkest blue portion of the imagery.