CLEARING Flashcards
Process whereby alcohol or dehydrating agent is removed from tissue and replaced with substance that will dissolve wax
Clearing
De-alcoholization
Most commonly used clearing agent for de-alcoholization in the embeddinv process are:
Xylene
Dioxane
Chloroform
Cedarwood
Used when the tissue is to be cleared directly from water as in a frozen section
Glycerin
Gum syrup
Make the tissue transparent due to high refractive index for better visualization
Clearinh agents
Steps requiring complete clearing
Infilltration
Mounting
Generally suitable for most routine histologic processing shedules <24hrs <5mm thickness
Xylene
Miscible with alcohol and paraffin
Xylene
Toluene
Doesnt extract out aniline dyes
Xylene
Used for celloidin section
Xylene
Becomes milky when an incompletely dehydrated tissue is immersed in
Xylene
Substitute for xylene and benzene but slower
Toluene
Best clearing agent for embedding
Benzene
Can damage the bone marrow resulting to aplastic anemia
Benzene
Thick blocks up to 1 cm can be processed with this clearing agent
Chloroform
Clearing agent doesnt not become translucent
Doesnt make tissue transparent
Chloroform
Recommended for tough tissues
Chloroform
Toxic to the liver after prolonged inhalation
Chloroform
Vapor attack the rubber seal
Chloroform
For both celloidin and paraffin
Cedarwood oil
Tissue with cedarwood oil initially float and may dry out before completely cleared
Prevented by?
Superimposing absolute alcohol of the surface of clearing agent
For clearing embryos, insects, delicate specimen
Aniline oil
Clear 70% alcohol without excessive shrinkage and hardening
Aniline oil
Tendency to become adulterated
Clove oil
Similar with chloroform but cheaper
Carbon tetrachloride
Slow acting clearing agents
Used when double embedding is required
Methyl benzoate
Methyl salicylate
Amyl acetate
Should not be used for nervous tissues and lymph nodes
Xylene
Fast acting for urgent biopsies
Xylene
Benzene
Tends to acidify partially filled vessel
Toluene
Tissues tend to float with this clearing agent
Chloroform
Extremely slow
Cedarwood oil
Becomes milky when prolonged storage
Cedarwood oil
For CNS and cytological studies
Cedarwood oil
Slow and difficult
Expensive
Clove oil
Faint pleasant odor
Terpineol
Substitute for cedarwood oil
Terpineol
For clearing skin and smooth muscle
Oil of bergamot
Use for delicate tissue
Oil of wintergreen
Aniline oil
Xylene substitute
Toluene (xylene and benzene)
N-butyl acetate
Limonene
Nitrocellulose solvent
N-butyl acetate
Amyl acetate
Methyl salicylate
Methyl benzoate
Obtained form citrus fruits
Limonene
