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Staining Onion Cells with Methylene Blue

  • Botany
  • In this staining onion cells with methylene blue post we have briefly explained about methylene blue principle, requirements, procedure, expected result and applications.

Staining Onion Cells with Methylene Blue

  • In methylene blue staining If an onion is placed atop a water-filled conical flask, the root can be easily grown.  In such a way that the onion disc comes into contact with water or sits on moist sand. The bulb is partially submerged in sand. In just two days, approximately 1cm long roots emerge. After that, we can trim, repair, and store it.


  • Methylene blue is charged positively.  When DNA and methylene blue come into contact, their opposite charges attract, allowing the rings of methylene blue to slide in between the strands of the DNA ladder resulting in a rich blue stain that identifies the cell nucleus’ position.



  • Prepare a saturated solution of methylene blue by adding 1.5 g powdered methy- lene blue to 100 mL 95% ethyl alcohol. Slowly add the alcohol to dissolve the powder. Add 30 mL saturated alcoholic solution of methylene blue to 100.0 mL distilled water and 0.1 mL 10% potassium hydroxide.


  1. Slides and cover slips
  2. Pasteur pipettes or droppers
  3. Glycerine
  4. Dissecting needles
  5. Filter paper and blotting paper
  6. Microscope
  7. Scalpel or blade
  8. Forceps
  9. Ethanol (70%)
  10. Stains-methylene blue.


  1. The root tip was cut using sterile blade and treat within 1 HCL for 1 Minute. This will soften the call wall.
  2. Transfer the root tip from 1N HCL to methylene blue stain and stain for 30 minutes. Place a cover glass on the root tip and Squash it using a rubber end pencil.
  3. Seal the edges of the cover glass and prevent drying, the stained preparation is ready for examination under the microscope.


Staining Onion Cells with Methylene Blue

Onion Cells with Methylene Blue stain

  • Large, rectangular interlocking cells, Clearly visible distinct cell walls surrounding the cells, Dark stained nucleus, Large vacuoles at the center, Small granules may be observed inside the cells (within the cytoplasm).

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