Clearing Flashcards
Is the process whereby alcohol or a dehydrating agent is removed from the tissues
Is done twice, during processing (embedding)and prior to permanent mounting
CLEARING
Clearing agent used
Xylene
Produces hardening, brittleness and shrinkage of tissue
ORGANIC SOLVENTS
Best result when preceded by absolute (100%) alcohol dehydration
Compatible with stains
Hardens tissues on prolonged exposure (limited to 3 hrs.)
Xylol (30 mins.-1 hr.)
Not suitable for CNS tissues and lymph nodes
Becomes “milky white” when tissue is inadequately dehydrated
Xylol (30 mins.-1 hr.)
May be used as a substitute for xylene or benzene for clearing both during embedding and mounting processes
Toluene (1-2 hrs.)
Rapid (15 mins.-1 hr.),hence is recommended for urgent biopsies and routine processes
It is highly flammable
It damages bone marrow leading to aplastic anemia
Benzene
Slower than xylol
It has no hardening effect
It is relatively toxic to the liver on prolonged inhalation
Chloroform
Very good clearing agent
It is recommended for large tissue and embryo
Amyl acetate
It is toxic on prolonged inhalation
Similar to chloroform but cheaper
Carbon tetrachloride
Combination of phenol and xylol
It is very rapid
It is used prior to permanent mounting
Carbol-xylene
It is slow
Are used in double-embedding technique
Dioxane
THF
Lead-free aviation gasoline
Methyl benzoate & methyl salicylate
Used for large and hard tissues
It allows indefinite stay of tissues
It is difficult to remove from tissue during infiltration
OILS
It produces no shrinkage
It may become “milky” on prolonged storage
Cedar wood oil (2-3 days)
It is recommended for embryos, insects and very delicate specimens due to its ability to clear 70% alcohol without excessive tissue shrinkage and hardening
Aniline oil
