Dehydrating and clearing agents Flashcards
For routine dehydration of tissues
Best dehydrating agent - fast acting
Not poisonous
Not expensive
Ethyl Alcohol
Toxic dehydrating agent
Primarily employed for blood and tissue films and for smear preparation
Methyl Alcohol
This dehydrating agent is utilized in PLANT and ANIMAL microtechnique
Slow dehydrating agent
Producing less shrinkage and hardening than ethyl alcohol
Recommend for tissue which do not require rapid processing
Butyl Alcohol
Routine dehydration process
70% alcohol - 6 hours
95% alcohol - 12 hours
100% alcohol - 2 hours
100% alcohol - 1 hour
100% alcohol - 1hour
Dehydration of tissue NOT more than 4mm thick
70% Ethanol -15 min
90% ethanol - 15 mins
100% Ethanol - 15 mins
100% ethanol - 15 mins
100% ethanol - 30 mins
100% Ethanol -45 mins
A cheap, rapid acting dehydrating agent
Dehydrates in 1/2 to 2 hours
More miscible with epoxy resins than alcohol
20:1 ratio (Fixative)
Clear, Colorless highly flammable and extremely volatile fluid
Rapid in action but penetrates tissues poorly and causes brittleness in tissues that are prolonged dehydrated
Most lipids are removed
Produces considerable tissue shrinkage
NOT RECOMMENDED for routine dehydration purposes
Acetone
Excellent dehydrating and CLEARING agent
Produces less tissue shrinkage
Tissues can be left for long periods of time w/o affecting the consistency or staining properties of the specimen
Tissue sections dehydration with this dehydrating agent tends to ribbon POORLY
EXPENSIVE and extremely dangerous (Vapor is toxic)
Formed peroxide may EXPLODE upon air exposure
Dioxane (Diethyl Dioxide)
Dehydrates rapidly
The tissue may be transferred from water or normal saline directly to cellosolve and stored in it for months w/o producing hardening or distortion
Caution: Ethylene glycol ether is combustible at 110F to 120F and is toxic
Propylene based glycol ether should be used instead
Cellosive (Ethylene glycol monoethyl ether)
Removes water
Produces very little distortion and hardening of tissues
Soluble in alcohol, water, ether, benzene, chloroform acetone, and xylene
Used to dehydrate SECTIONS AND SMEARS
Triethyl Phosphate
BOTH DEHYDRATES and CLEARS tissues since it is miscible in water and paraffin
Can be used for demixing, clearing, and dehydration paraffin sections before and after staining
Causes less shrinkage and EASIER cutting of sections with FEWER artefacts
Does NOT dissolve aniline dyes
TOXIC if INGESTED or INHALED
Vapors causes nausea, dizziness, headache, and anesthesia
Tetrahydrofuran
Added to each 95T ethanol bats as part of dehydration process
Acts as a softener for hard tissues
4% Phenol
Dehydrating agent for Electron microscopy
Accompanied by PROPYLENE OXIDE as a transition fluid
Along with propylene oxide, this solvent have some undesirable propery
Ethanol
A good substitute for propylene
Non-carcinogenic, less toxic, and not as flammable as propylene oxide
Excellent dehydrating agent
Acetonitrile
Colorless clearing agent that is MOST COMMONLY used ⭐
Most rapid clearing agent, suitable for urgent biopsies
Clearing time is 1/2 hour to 1 hour
Makes tissue transparent
Does not extract aniline dye
Can be used for Celloidin sections because it does NOT dissolve celloidin
NOT suitable for nervous tissue and lymph nodes
CHEAP
Xylene
May be used as a SUBSTITUTE OR ALTERNATIVE ONLY for xylene or benzene ⭐
Clearing time is 1 - 2 hours
Acts fairly rapidly and is recommended for routine purpose
Tissues do not become excessively hard and brittle even if left for 24 hours
NOT carcinogenic
SLOWER than xylene and benzene
EXPENSIVE
Toluene
Preferred as a clearing agent in the embedding process of tissues because it penetrates and clears tissues rapidly
Clearing time is 15 to 60 minutes
Does not make tissues hard and brittle but it causes MINIMUM SHRINKAGE
Makes tissues transparent
FLAMMABLE
TISSHUE SHRINKAGE may be OBSERVED if left for a long time
Excessive exposure is TOXIC and CARCINOGENIC to human
May damage the bone marrow resulting in APLASTIC ANEMIA ⭐
Benzene
Slower in action than xylene but causes less brittleness
Suitable for LARGE TISSUE SPECIMENS. Thicker blocks can be processed
Clearing time 6-24 hours
Recommended for NERVOUS TISSUES, LYMPH NODES, and EMBRYOS ⭐
NOT FLAMMABLE
Relatively toxic to the LIVER after prolonged inhalataion
Wax impregnation after this clearing agent is relatively slow
DOES NOT make tissue transparent
Difficult to REMOVE from paraffin section because it is NOT very volatile
Complete clearing is difficult to evaluate
Chloroform
Advantages and Disadvantages are the same with chloroform ⭐
Produces CONSIDERABLE tissue HARDENING and DANGEROUS to inhale on prolonged exposure due to its highly toxic effects
Carbon tetrachloride
Used to clear both PARAFFIN and CELLOIDIN sections during embedding process
Recommended for CNS tissues, and Cytological studies
CCC = _____ , CNS, Cytological
Very penetrating agent
Becomes MILKY upon prolonged storage and should be filtered before use ⭐
VERY EXPENSIVE
Extremely slow clearing agent, not for routine purposes
Clearing time is 2-3 days
Celloidin clearing is 5-6 days
Cedarwood oil
Not normally utilized as a clearing agent
Recommended for clearing embryos, INSECTS, and VERY DELICATE SPECIMENS due to its ability to clear 70% ALCOHOL without excessive tissue shrinkage and hardening ⭐
Aniline oil
Causes MINIMUM shrinkage of tissues
Its quality is not guaranteed due to its tendency to become ADULTERATED ⭐
Wax impregnation after clearing with this clearing agent is SLOW and DIFFICULT
Tissues become BRITTLE, aniline dyes are REMOVED and celloidin is DISSOLVED
EXPENSIVE and UNSUITABLE for routine clearing purposes
Clove oil
Slow-acting clearing agents that can be used when DOUBLE EMBEDDING techniques are required ⭐
OIL OF WINTERGREEN
Methyl benzoate and Methyl Salicylate
For frozen section
No de-alcoholization is involved in this process
Glycerin and gum syrup
