H&E Flashcards
Why is H&E widely used
Simple and demonstrates different tissue structures
What is haematoxylin
Haematoxylin oxidised to haematein
Haematein forms dye lake with metal salt mordant to gain a charge and stain tissue structures
What are the 3 types of heamatoxylin
Aluminium
Iron
Tungsten
Name the 2 iron heamatoxylins used
Weigarts and Verhoeff
What colour does aluminium heamatoxylin stain and how can it be stained
Nuclei = Red, this becomes blue-black when washed with tap water (weak alkali) - bluing
Alum H can be stained progressively (right time) to stain nuclei only
or
regressively and then differentiated with alcohol
Disadvantage of haematoxlylin and how it is overcome
Sensitivity to subsequent acidic staining solutions (Van Gieson counterstain)
Instead used weigarts haematoxylin which is resistant to acid
Role of iron salts in iron haematoxylin
Oxidising agent and mordant
Why is iron heamatoxylin better than aluminium
It stains wider range of tissue structures
But is more time consuming
Eosin
Used to distinguish cytoplasm, connective tissue and matrices
Used for differentiation and stains shades of red & pink
Quality control - improving staining
Different H&E types - different timings
Age of stain affects properties
Fixation and tissue sectioning - thickness
Pale pink cytoplasm
Eosin pH - incomplete removal of bluing agent (too high or low pH depending on what was used)
Dark nuclei and blue cytoplasm
Inadequate differentiation
Blue-black precipitate
Haematoxylin needs filtering to remove dye lake (alum-haematein) crystals
Hazy blue nuclei
Too much heat
Not enough time for staining
Reddish brown nuclei
Aged haematoxylin
