L.2 Haematoxylin & Eosin Flashcards
What is Haematoxylin?
A natural dye extracted from the bark of a tree.
What is required for Haematoxylin to have staining properties?
Processing to haematin.
What is the first step in processing Haematoxylin?
Oxidation.
What chemicals are used for the oxidation of Haematoxylin?
- Sodium iodate
- Mercuric oxide
What is Haematin?
A weak anionic purple dye with no affinity for nucleic acids of nuclei.
What is the role of a mordant in staining?
Provides the dye with a positive charge to bind to anionic nuclear chromatin.
What are some examples of mordants?
- Ammonium alum
- Potassium alum
- Ferric salt
Which staining method is most frequently used in histology?
Haematoxylin and Eosin.
What color do Harris, Mayer, and Gill Haematoxylin stains produce?
Stain nuclei blue.
What color does Weigert Haematoxylin stain produce?
Stains nuclei black.
What is the staining result of Verhoeff Haematoxylin?
Stains elastic black.
What is progressive staining?
When tissue is left in the stain just long enough to reach the proper endpoint.
What is regressive staining?
Tissue is overstained and then destained until the proper endpoint is reached.
What does differentiation refer to in staining?
Selective removal of stain from tissues.
What is the function of mordants in staining?
Help ‘fix’ or bind a dye to tissue structures.
Why do some stains require mordants?
They do not bind strongly enough to tissue components.
What is an example of a mordant that binds Haematoxylin to DNA in nuclei?
Alum.
What is an example of an iron salt used as a mordant?
Ferric chloride.
