Histology & Cytology Flashcards
What is Histology?
Tissues are processed to see malignancy under microscope. Can be fresh or fixed.
Fixation
- Submerged in solution ASAP
- 10-20x volume of specimen
- Solution denatures protein (prevents autolysis)
- Usually neutral buffered formalin (rarely glutaraldehyde or B5)
Grossing
- Description done by pathologists
- Sliced into 3-5mm pieces to go into cassettes
Decalcifying
- Removes calcium from bone or scar tissue
- Must be fixed before decalcified
Dehydration
Removal of water using increasing strengths of alcohol (ethanol or acetone)
Clearing
- Removal of dehydration agent using xylene (could be toluene or histoclear)
- Decreases the cloudiness of a specimen (poor dehydration = milky xylene (water in xylene)
Infiltration
- Removal of clearant
- Infiltration of paraffin wax (must be dewaxed before stain or stain won’t penetrate)
Mounting
Permount + coverslip
Resinous Mount
Permount, aqueous mount, gelatin
STAT Processing
- 2-4 hours instead of 12-16
- Sections frozen by cryostat
- Cut with microtome
- Frozen, cut, stained, viewed
- Specimen is then thawed and processed as normal
- Tech SETS UP
Stains: Hematoxylin-Eosin (H&E)
Hematoxylin - Blue
Eosin - Red/orange/pink (differential stain)
Stains: Progressive
Specimen left in dye until it’s ready
Stains: Regressive
Specimen is over stained and excess stain is removed
Bluing
- Must be mildly alkaline
What’s the most important step of Bluing?
Differentiation
What is Cytology?
- Less traumatic sampling
- Relies on good samples
- Can be fresh or fixed
- Liquid based or cell block
Stains: Pap
Fixative = Alcohol
Hematoxylin = Aqueous
Counterstain = Alcohol
Clearing = Xylene
Stains: DiffQuick
Rapid Romanowsky (stain)
- Eosin-methylene blue
- 10 dips in methanol to fix
- 5 dips in eosin
- 10 dips in methylene blue/azure
- Water rinse
Stains: Retic Stain
Supravital stain = saline + methylene blue/brilliant cresyl blue + 15 mins
Too thick blood smear?
Too big of blood drop
If your Hematoxylin has a sheen, it needs what?
To be filtered
If your Wright’s stain is too blue, it’s what?
Buffer is too acidic