Posted in Staining


MORDANT and ACCENUATOR both are terms used in staining, for substances which enhance staining. However, both have different mechanisms of action. We will be looking at the difference between mordant and accenuator in staining.

Differences between mordant and accenuator


  1. MORDANT serves as a link or bridge between the tissue and the dye, to make the staining reaction possible.
  2. The mordant combines with a dye to form a colored “lake”, which in turn combines with the tissue to form a “tissuemordant-dye-complex”.
  3. Examples of mordants are potassium alum with hematoxylin in Ehrlich’s hematoxylin, and iron in Weigert’s hematoxylin.

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  1. ACCENTUATOR, is not essential to the chemical union of the tissue and the dye.
  2. It does not participate in the staining reaction,
    but merely accelerates the reaction.
  3. Examples are potassium hydroxide in Loeffler’s methylene blue and phenol in carbol thionine and carbol fuchsin.
Posted in Histopathology, Staining

10 Key points- Hematoxylin and Eosin staining in Histopathology

Key points in Hematoxylin and Eosin staining

  1. Hematoxylin is extracted from the heartwood of the tree Hematoxylin campechianum.
  2. Hematoxylin is not a stain itself. Hematin, a major oxidation product of hematoxylin is responsible for the color.
  3. Hematin is produced in two ways (a) Natural oxidation OR Ripening (b) Chemical oxidation.
  4. Ripening is done by exposing the solution to light and air. This is a slow process and takes up to 3-4 months.
  5. Ehrlich’s hematoxylin and Delafield’s hematoxylin are obtained by natural oxidation.
  6. A mordant is a substance, usually a metal which helps bind the dye with the tissue strongly.
  7. Sodium Iodate is the mordant used in Meyer’s hematoxylin and Mercuric Oxide used in Harris hematoxylin.
  8. Aluminum is the most common mordant.
  9. Carrazi’s hematoxylin has a staining time of 1 minute- shortest time for any hematoxylin stain. Hence it is used to stain frozen section slides.
  10. Iron hematoxylins are preferred connective tissue stains. Due to the acidity of dye solutions in connective tissue staining ( picric acid in Van Gieson staining), standard alum hematoxylins are decolorized. Iron hematoxylins such as Wiegert’s hematoxylin are resistant to the acidic environment and should be used in these techniques

Examples of ALUM HEMATOXYLIN are:

1. Erhlich hematoxylin

2. Delafield hematoxylin

3. Meyer hematoxylin

4. Harris hematoxylin

5. Cole hematoxylin

6. Carrazi’s hematoxylin.

Check out this post on Carbohydrate staining.

Examples of IRON HEMATOXYLIN are

1. Weigert’s

2. Heidenhain’s

3. Loyez for myelin

4. Verhöeff’s for elastin fibers.