Visualize cell nuclei in eukaryote cells.


  • Gas burner
  • 95% alcohol
  • Loeffler’s methylene blue solution
  • Tap water
  • Bucket or beaker glass
  • Blotting paper (alternatively: Tork roll or toilet paper)
  • Clear nail polish
  • Acetone
  • Cotton swab

Composition of the stain

  • Methylene Blue 3.0 g
  • Potassium Hydroxide KOH, 10% 1.0 ml
  • Ethanol, 95% 300.0 ml


  1. Prepare a drop of sample on your microscope slide according to our Method
  2. Air dry the sample for 5 to 10 minutes.
  3. Soak the cells in a drop of 95% alcohol to dehydrate the cells
  4. Air dry the sample for 5 to 10 minutes, make sure all the alcohol is evaporated
  5. Fixate the cells by quickly moving the object glass through a flame.
  6. Let the sample cool down.
  7. Add the Loeffler’s solution for about 60 seconds.
  8. Remove excess stain by bathing / dipping your glass slide into a beaker glass / bucket with tap water.
  9. Remove excess water using blotting paper.
  10. Let the slide air dry to get rid of the remaining water.
  11. Put 2 drops of clear nail polish onto the sample.
  12. Cover the sample with a cover slide.
  13. Try to get rid of air bubbles by putting light pressure on the cover slide.
  14. Remove excess nail polish with a cotton swab with acetone.
  15. Take a look at the sample through the microscope with the diaphragm fully open.

Loeffler stain

Microscopic image of onion cells stained with methylene blue, so the nuclei are visible. Magnification: 100x. - Picture by Umberto Salvagnin CC BY 2.0 license

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