CLEARING Flashcards
Colorless
Characteristic petroleum or aromatic odor
Miscible with organic solvents and paraffin
Suitable for blocks that are less than 5mm in thickness
Over exposure produces hardening
Most common clearing agent (1/2 to 1 hour)
Recyclable
__ becoming __ = incomplete dehydration
Xylene
MILKY
Similar properties to xylene Clearing \_\_ hrs Less damaging with prolonged immersion More volatile than xylene Tends to acidify in a partially filled vessel
TOLUENE
1-2 hours
Rapid action (15-60 minutes)
Volatizes rapidly in paraffin oven and is therefore easily eliminated
Causes tissue shrinkage
__
BENZENE
Carcinogenic
Slower in action than xylene Causes less brittleness Can be used to process \_\_ Recommended for tough tissues (decalcified tissues), nervous tissues, lymph nodes, and embryos Tissues do not become translucent Non-flammable but highly toxic Liberates \_\_\_ _ when heated Tissues float Often used for \_\_ specimens
CHLOROFORM
thicker blocks
PHOSGENE GAS
CNS
Used to clear both paraffin and celloidin sections
Good for CNS and cytological specimens (particularly smooth muscles and skin)
Time = __ days
Slow
Hard to eliminate from tissues in paraffin bath
Quality is not uniform and not always good
Becomes milky with prolonged storage
May produce crystals with __ fixatives with a melting point of __c = heated to __ to dissolve crsytals
CEDARWOOD OIL 2-3 days Acetic-Alcohol fixatives 35C 200C
Not normally utilized
Recommended for clearing embryos, insects and very delicate specimens
ANILINE OIL
Causes minimum shrinkage of tissues Quality is not assured because it is usually adulterated Slow and difficult to use Tissues become brittle Aniline dyes are removed \_\_ is dissolved
CLOVE OIL
Celloidin
Used for clearing and embedding
Similar to chloroform
Highly toxic
CARBON TETRACHLORIDE
Dehydrates and clears at the same time
Non toxic
Offensive odor
TETRAHYDROFURAN
Slow acting
Used in double embedding techniques
METHYL BENZOATE & METHYL SALICYLATE
Extracts from oranges and lemon rinds Non toxic Miscible with water Easily disposed with water Strong pungent odor May dissolve small tissue deposits like calcium and copper
CITRUS FRUIT OILS
LIMONENE REAGENTS
Fractional distillation may be used to recycle alcohol and xylene based on differing boiling points
RECYCLING AGENTS
Reduced cost
Rapid
Efficient
Eliminates the need to have chemicals removed by a waste disposal company
Environmentally unsafe chemicals are not being sent to landfills for disposal
RECYCLING AGENTS
