Clearing Flashcards
Removal of dehydrating agent from the tissue
Clearing
Most common dehydrating agent __________ , specifically_____________.
Alcohol; Ethanol
Another term for clearing
Dealcoholization
Process of Dealcoholization
Fixation - Decalcification - Dehydration - Clearing
Purpose of Clearing
- Removing of dehydrant from tissue, and replacing it with a fluid miscible to both dehydrant and embedding agent.
- Makes tissues transparent
- Flammable fluids have low boiling points
Not miscible with paraffin (most common infiltrating medium)
Ethanol
Characteristics of a good clearing agent
- Miscible w alcohol
- Miscible w paraffin wax
- not produce tissue shrinkage
- make tissue transparent
- not dissolve aniline dyes
- not evaporate quickly in a water bath
Most common
Advantages
- Rapid, suitable for urgent biopsies
- Makes tissue transparent
- Miscible both alcohol & paraffin
- Cheap
Disadvantages
- Highly flammable
- 3 hrs, makes tissue hard
- Not suitable for nervous tissues and lymph nodes
Xylene (1/2 to 1 hr)
Advantages
- Miscible bath water and paraffin
- Does not make tissues hard and brittle.
Disadvantages
- Slower than Xylene
- More expensive
Toluene (1-2 hours)
Chloroform 6-24 source
Tough tissues and large specimens (kin, Fibroid & Decalficied tissues
For Insects, embryos, and delicate tissues
Aniline Oil
Not suitable for routine purposes
Minimum shrinkage of tissues
Slow, expensive and difficult to use
Clove oils
Similar to chloroform but cheaper
Dangerous to inhale on prolonged exposure
Carbon Tetrachloride
Can perform dehydration and clearing
Shorter processing time
Offensive ethereal odor
Non-toxic but with offensive and should be used in well-ventilated room.
Tetrahydrofuran
Causes greater shrinkage than Xylene
Dangerous, toxic to liver
Dioxane
