Frozen Sectioning Flashcards
What are the principles of frozen sectioning?
Sample is not processed
Tissue becomes firm by freezing it
Ice crystals provide support for cutting thin sections
Water within tissue is frozen quickly
What are the main reasons for creating slides on the cryostat?
- Stat samples – patient in the OR and surgeon wants a result within 15 minutes. Cut on cryostat and do a rapid H&E. Pathologist examines slide right away and reports to the OR.
- Lipids, etc. - Want to demonstrate lipids or other elements of tissue that may be removed during processing
- Histochemistry
- Fluourescent antibody techniques
What are the advantages of frozen sectioning / cryostat use?
- Rapid diagnosis – eliminate the need to process tissue
2. No shrinkage of tissue
What are the disadvantages of frozen sectioning / cryostat use?
- Structural details poor
- Thicker section
- Ice crystal artifact
- No ribbons
- Biohazard concerns with fresh tissue
How are tissues treated / prepared for cryostat?
TISSUE – FRESH or 10% NB FORMALIN – WASHED!
What precautions must be taken with the tissue intended for frozen sectioning?
Fresh tissues are treated with Routine Practices.
What are the waste removal considerations for frozen sectioning?
All waste must go in biohazard bags and be autoclaved or incinerated.
What kind of embedding medium is used when frozen sectioning on a cryostat?
Water based embedding medium
Name some cryostat parts?
Chuck Holder
Freezing Bar
Anti-roll device (face Plate)
A cryostat is basically a __________ _________ inside a __________.
rotary microtome
freezer
Fresh tissues are usually quickly frozen at what temperature range?
Quickly frozen at - 10°C to -30°C, dependent on the tissue type.
What is brain and lymph node typically frozen at?
Brain and lymph node at -10°C.
What is liver, kidney, and spleen typically frozen at?
Liver, kidney, and spleen at -15degC
What is muscle and thyroid typically frozen at?
Muscle and thyroid at -20C,
What are these tissues typically frozen at?
a) Skin
b) Breast or other tissues with adipose tissue?
a) Skin at -25C,
b) Breast or other tissues with adipose tissue -30C
What are the typical section thickness for cryotomy?
The section is cut at 6 to 10 um thick. Unable to cut any thinner than that.
Describe the cryotomy process?
Single section is cut. You can use the face plate or a tiny paint brush to gently drag the specimen across the cutting surface to prevent it from rolling up. Then you touch a room temperature slide down to the specimen.
What daily maintenance should be done on a cryostat?
- Daily check of temperature before use.
- Regular defrosting and
- Regular disinfection
- Low temperature oil & grease
What safety considerations are required for the cryostat work area (6)?
- Unfixed tissue is potentially infectious
- Gloves, mask, goggles, gown
- Restrict work area
- Restrict # of instruments
- Restrict # of staff
- Pick up debris with gauze dampened with alcohol
What are the basic steps of frozen sectioning?
- Obtain tissue sample
- Prepare tissue holder
- Water based medium
- Rapid freeze
- “Rough in” tissue
- Set anti-roll device
- Fine cutting
- Pick up tissue section
For decontamination can you use sodium hypochlorite?
NO, cannot use Na Hypochlorite
What is used on cryostats for daily decontamination?
Daily decontamination
- 70% Ethanol (solution) – daily cleaning (not necessary to shut down unit)
- New cryostats – UV or ozone
What is used on cryostats for weekly decontamination (if used often)?
Weekly (if used often)
shut off freezing unit and clean thoroughly with something that can kill TB and HIV, HBV, etc.
95% alcohol, Glutaraldehyde vapour or 40 % formaldehyde vapour can be used.
What to do if? Possible reasons/Remedies.
Tissue breaks off the specimen holder.
Causes
- Not enough contact between specimen and holder because of air trap
- Roughing in too much
Remedies
- Use ample amounts of OCT on specimen holder
- Take smaller increments
