CLEARING Flashcards
PURPOSE OF CLEARING
- Removing dehydrant from tissue, and replacing it with a fluid miscible to both dehydrant and embedding agent.
- Makes tissues “translucent” or transparent, hence the term clearing.
- Most are flammable fluids and have low boiling points
- Excessive clearing may cause brittleness
CHARACTERISTICS OF GOOD CLEARING AGENT
• It should be miscible with alcohol.
• It should be miscible with paraffin wax.
• It should not produce tissue shrinkage.
• It should make tissue transparent.
• It should not dissolve aniline dyes.
• It should not evaporate quickly in water bath
Alcohol clearing agents
Xylene
Toluene
Benzene
Time to complete CLEARING
XYLENE
30mins to 1hr
Time to complete CLEARING
TOLUENE
1-2hrs
Time to complete CLEARING
TOLUENE
1-2hr
Time to complete CLEARING
BENZENE
15mins-1hr
• rapid, suitable for urgent biopsies
• Makes the tse transparent
• Miscible both in alcohol and paraffin
• Cheap
XYLENE
・ Miscible both in alcohol and paraffin
・Does not make tse hard and brittle
・Not carcinogenic
TOLUENE
• For URGENT biopsies
• Fastest clearing agent
BENZENE
Highly flammable
> 3 hours, makes tse hard
Not suitable for nervous tissues and lymph nodes
XYLENE`
Slower than xylene
More expensive
TOLUENE
Carcinogenic
May lead to aplastic anemia
BENZENE
Time to complete CLEARING
CHLOROFORM
6-24hrs
Time to complete CLEARING
CEDARWOOD OIL
2-3days