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Histology ASCP

ASCP Histology Tech: Processing/Instrumentation

dehydrating agents alcohol, acetone, dioxane, tetrahydrofuran (last two are universal solvents)
incomplete dehydration results in mushy soft sections
the dye-check solution of eosin can only be added to ________, not isopropanol ethanol (dehydratant)
__________ cannot be used in processors or with isopropanol Drierite (dehydratant)
clearing agents must be miscible with ______ and _______. dehydratant and paraffin
a reagent that CANNOT be used for dehydrating tissues is: benzene (clearnat)
paraffin used for embedding is ___ degrees celsius. 53 degrees celsius
one disadvantage using dioxane for processing is it is TOXIC
one xylene disadvantage is it is likely to harden tissue
routine use paraffin melting point should be 55 to 58 degrees C
which is not a clearing agent? chloroform/ethanol/dioxane/xylene ethanol (dehydratant)
overheating of paraffin used for embedding may cause cracking of the block
one advantage of paraffin use is serial sections are easy to obtain
when cutting a block, if the tissue seems hard and brittle... overheated paraffin
SOFT paraffin is most useful when _______ sections are desired. thick
when used for clearing, cedar wood oil must be followed by xylene (clearant)
paraffin is cooled rapidly as possible after embedding to prevent formation of large crystals
dehydration and clearing steps can be omitted when using water-soluble wax (embedding medium)
ETHYL ALCOHOL BEST DEHYDRATANT!!! PEL=1,000 / 60-65-95-95-absolute
denatured alcohol ethanol + methanol or ethanol + isopropanol (dehydratant)
METHYL ALCOHOL POISONOUS dehydratant, NOT USED ALONE PEL=200 / not for skin; breaks down to formaldehyde; causes blindness and death
Dioxane a UNIVERSAL SOLVENT which is faster, less shrinkage than ethanol, toxic, rarely used / PEL-OSHA=100 /PEL-NIOSH=1
Acetone (dehydratant) PEL-OSHA=1,000 / PEL-NIOSH=250 / (rapid, cheap, but absorbs water from the air) USED IN TOUCH PREPS OR FAST FIXES. CAN ALSO BE USED LIKE A UNIVERSAL SOLVENT.
Tertiary Butanol (dehydratant)odorous, expensive, solidifies at room temperature,MIXES WITH WATER, ETHANOL, XYLENE / PEL=100
Tetrahydrofuran a universal solvent that is miscible in lower alcohols, water, xylene, toluene, benzene, chloroform, acetone,melted parrafin. less toxic than dioxane. PEL=200 / offensive odor, causes conjunctivitis/ BEST UNIVERSAL SOLVENT
PEL=100 / used as clearing agent in most labs xylene (clearant)
Toluene BEST HYDROCARBON CLEARING AGENT, PEL=50, STEL=150 /not as hard as xylene
Benzene fast, does not over-harden, WILL HARDEN MUSCLE, TENDON, UTERUS more than TOLUENE // PEL=10
CHLOROFORM PEL=50 chloroform is carcinogenic
water soluble waxes CARBOWAX: dehydrating and clearing unnecessary. Infiltrates tissue directly from fixative.BAD: floating out occurs
a nitrocellular compound used for embedding (i. Parloidion). storage blocks held in 80% alcohol. hardened with chloroform. mixed with ether and absolute alcohol to prepare. celloidin
great for undecalcified bone, kidney, bone marrow, lymph node biopsies GMA Glycol Methacrylate , acrylic resin which is miscible with water.
5% aqueous formic acid will decalcify most bones in 3 to 5 days
celloidin MUST BE dehydrated
ethylene glycol monoethyl ether a dehydratant that retains tissues for extended periods of time. more than ethanol or 70% alcohol
sections processed by _______ method show less shrinkage than when processed by paraffin. celloidin
best processing for enzyme demonstration frozen sections
ion exchange resin & electrolytic methods of decalcification are considered acid methods
these agents EDTA)bind certain metals chelating agents
30% sucrose best way to get frozen sections from formalin fixed, unprocessed tissue, by infiltrating in this
Created by: alexinem