Haematoxylin & Eosin Flashcards
What is Blueing in histology?
The pH of haematoxylin is low, and the dye is pink; washing in tap water raises the pH and converts haematoxylin into a blue insoluble form which is more stable and contrasts better with counterstains.
What is the purpose of differentiation in histology?
Allows the selective removal of excess dye from components which have weakly bound the dye, resulting in the nuclei remaining stained and cytoplasm clear.
What is a mordant?
A substance/metal which chemically binds with dye and acts as a link between dye and tissue.
What does haematoxylin oxidation produce?
Haematin, which has colour properties but a poor affinity for tissues and does not stain nuclei when used alone.
How do mordants improve staining with haematin?
Adding mordants such as aluminium or iron improves the affinity of haematin to tissues allowing stronger staining.
What is the standard morphological stain worldwide?
H&E (Haematoxylin and Eosin).
What does haematoxylin stain?
Nuclei -> Blue (Haematoxylin)
Cytoplasm -> Pink (Eosin)
What type of dye is haematoxylin?
Basic dye, aluminium-mordanted, stains regressively.
What is the staining behavior of eosin?
Eosin is an acid dye that will stain all components unstained by haematoxylin and is termed a counterstain.
What are the criteria for a good haematoxylin stain?
- Chromatin detail
- Colour
- Differentiation
What are the criteria for a good eosin stain?
- Contrast
- Variation in colour in tissue component
Fill in the blank: Haematoxylin staining is characterized by a change in color to _______ after washing in tap water.
blue
True or False: Eosin requires differentiation to stain components.
False
What is used for differentiation?
1% acid-alcohol
What is the effect of washing haematoxylin with tap water?
Raises pH, converting it into a blue insoluble form.
What is the relationship between negatively charged groups in tissues and haematoxylin?
Negatively charged groups in tissues bind the dye, with the nucleus staining most intensely.
