Clearing (Lab) Flashcards
Serves as a bridge between dehydration and infiltration
Clearing
Clearing agents are miscible with both ________ and _________
Ethanol & Paraffin Wax
The goal of clearing
make the tissue clear
What property of clearing agents causes high transparency to tissues
High Refractive Index
The choice of clearing agent depends on what factors?
- type of tissue
- type of processing and processor system
- intended processing conditions
- safety factors, cost and convenience
Clearing agent used for automated processes
Xylene
Most common clearing agent
Xylene
Soaking an incompletely dehydrated tissue in xylene will cause what appearance
Milky
Xylene is not preferred for what type of tissue
CNS tissues
Procedure for Xylene
20min - 20min - 45min
Process whereby alcohol or a dehydrating agent is removed
Clearing
Used for clearing when the tissue is to be cleared directly from water (ex: Frozen sections)
Glycerin and Gum Syrup
Clearing agent used for when no dealcoholization is involved
Glycerin and Gum Syrup
Characteristics of a good clearing agent
- should be miscible with alcohol
- should be miscible and easily removed by melted paraffin wax
- should not produce excessive shrinkage, hardening and damage of tissue
- should not dissolve out aniline dyes
- should not evaporate quickly in a water bath
- should make tissue transparent
Another name for Xylene
Xylol
Clearing time for Xylene
1/2hr to 1hr
Clearing time for Toluene
1 - 2hrs
Clearing time for Benzene
15 - 60mins
Clearing agent used for larger or thicker tissue blocks (up to 1cm)
Chloroform
Tissues placed in this clearing agent do not become translucent
Chloroform
“Routine work” is how many hours?
6 - 24hrs
Used to clear both paraffin and celloidin sections during embedding process
Cedar Oil
Clearing agent recommended for CNS tissues and Cytological studies
Cedar Oil
Usual clearing time for Cedar Oil
2 - 3 days
Cedar Oil can clear _______ in 5 to 6 days
Celloidin
Clearing agent that is able to clear 70% alcohol
Aniline Oil
Clearing agent that is able to perform two processes at the same time
Tetrahydrofuran
Clearing time for Dioxane
4 hrs
How many times does Dioxane change within 4 hrs
3
Earliest transition solvents to be used in histology
Terpenes
A natural oil found in the skins of citrus fruits
Limonene
Clearing action with the lowest hazard rating of all xylene alternatives
Orange Oil Based clearing agents
Government regulations have restricted most of the effective solvents in this class
Chlorinated Hydrocarbons
Has the tendency to get solidified at a lower temperature
Coconut Oil
This transition agent can also be used as an dealcoholization agent
Coconut Oil
Present as a barrier to wax infiltration
Fat
Preferred for processing brain tissues
Toluene
Best transition agent
Benzene
Often used on dense tissues
Chloroform
Clearing agent that is an almost colorless mixture of isomers with a faint pleasant odor and very low evaporation rate
Terpineol
Terpineol clears tissue from how much concentration of alcohol
80% - 90% alcohol
Is a particularly useful substitute for Cedarwood Oil
Terpineol
Clearing agent that rapidly clears tissues from 95% alcohol
Cedarwood Oil
Formation of Crystalline Cedrol in Cedarwood Oil can be overcome by?
Addition of 1ml Xylene/Toluene to 80ml Cedarwood Oil
Temperature of Vacuum when restoring exhausted Cedarwood oil
60 degrees Celsius
When restoring exhausted Cedarwood Oil, how long must it stay in the vacuum
30 - 60mins
What process clears tissues after dehydration to prepare the tissues for its exposure to wax
Embedding Process
These are clear tissue sections after they have been stained to prepare it for microscopic evaluation
Mounting Tissues
Name 5 organic solvents
- Xylene
- Toluene
- Benzene
- Chloroform
- Terpineol
What is the ratio of Xylene/Toluene to Cedarwood Oil when overcoming Crystalline Cedrol
1:80
Cedarwood Oil is largely composed of what?
Cedrene
Odor of Terpineol
faint Pleasant odor
Evaporation rate of Terpineol
Very low
When Dioxane is used, 3 changes are made in a total of how many minutes?
90mins
