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