Tissue staining and types of stains Flashcards
what are the steps of tissue staining
1) tissue processing
2) sectioning
3) staining
what are the steps of tissue processing
1) fixation
2) Dehydration
3) Clearing
4) Embedding
Describe the steps of tissue processing
1) fixation:
-Putting the tissue in formaldehyde/ formaline
- 1-2 hours
2) Dehydration:
-Dehydrating the cell by introducing rising concentrations of alcohol into the cell to remove water
- 5-10 hours
3) clearing: Removal of alcohol by xylene
4) Embedding: Introducing paraffin in the cell then left to harden
Why is the tissue preserved in formaline/ formaldehyde
To preserve the tissue and prevent autolysis
Why is the tissue section dehydrated
To be able to insert paraffin as parafin and water don’t mix
Why is xylene used
As alcohol doesn’t mix with parafin
why is paraffin used
-It solidifies at root temprature
-It has a low melting and boiling point, lower than tissue
How thick are the tissue sections
4-5 μm
How is the tissue sectioned
using a microtome
Why are tissue sections floated on a warm water bath
to remove wrinkles
Why are tissue sections cut thin
To allow light to pass through
Describe the steps of staining the tissue
1) Deparaffinization:
-Removal of wax for staining by melting the wax
2) Clearing:
-Adding xyline to remove paraffin
-Adding decending concentrations of alcohol to introduce water and remove xyline
3)Apply the stain (wohooo)
What are the types of stains
Basic routine stain
Special stain
Immune reaction based staining
Which stain is used for basic routine stain
Hematoxylin and Eosin (H&E)
What does hematoxylin stain
-basophilic stain (alkaline)
-stains nucleus dark blue
What does Eosin stain
-eosinophilic stain (acidic)
-stain cytoplasm and collagen pink
What are the types of special stains
Masson trichome stain
Verhoeff Van Greson stain
Sudan III stain
Silver stain
Orcein stain
What does Masson trichome stain
Stains collagen bundles green/ blue
What does Verhoeff Van Gerson stain
Stains elastic fibres black
What does Sudan III stain
stains fat/ adipose cells orange
What is the exception for Sudan III stain
The tissue section needs to be a frozen section so the fat isn’t disolved by alcohol during dehydration
How is the tissue sample frozen
In a chryostat
What does silver stain
Stains reticular fibres black/ dark brown
What is immune reaction based staining
Method for detecting antigens in the tissue by using antigen-antibody reaction
What are the 2 types of immune reaction based staining
Immunohitochemical staining
Immunofluorescence staining
