Stains are used in microscopy to help view bacteria, which are normally colorless and hard to see in their natural state even with a microscope. 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.
The Eosin Y stain is used in concentrations from 1 to 5 percent weight, dissolved in water or ethanol. It can be seen with white light, but ultra-violet will yield stronger definition. For best results, follow the sequence below:
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.
Done correctly, four different color intensities may be seen: - Cytoplasm will stain pink-orange - Nuclei will stain dark blue or purple - Red blood cells will stain vivid red.
Thymol is often added for mold prevention, and acetic acid (.5%) will bring out darker red stains in tissue.