02 Dehydration Flashcards
pre-eminent type of tissue processing treatment considered to be the most suitable for routine preparation, sectioning, staining, and subsequent storage of large tissue samples
Paraffin wax method
paraffin wax method uses a series of ___ as dehydrating fluid
alcohol
the first step in tissue processing by which the intercellular and extracellular water from the tissue are removed after fixation and prior to wax infiltration
dehydration
solvents utilized in the removal of water
dehydrating agents/dehydrants
the removal of water from aqueaous-fixed tissue
dehydration
since most alcohols and paraffin are not miscible, another step, known as ___ is introduced
clearing
T/F: a dehydrating solution should evaporate very fast
F
It is important for a dehydrating solution to be able to dehydrate ___ tissues
fatty
T/F: a dehydrating solution should not harden tissues excessively and should remove stains
F (should NOT REMOVE stains)
dehydrating agent:
recommended for routine dehydration of tissues and considered the best dehydrating agent
ethyl alcohol
dehydrating agent:
clear, colorless, flammable fluid
ethyl alcohol
dehydrating agent:
primarily used for blood and tissue films, and for smear preparations
methyl alcohol
T/F: methanol is toxic to the body
T
T/F: ethanol is not poisonous
T
dehydrating agent:
utilized in plant and animal micro-techniques
butyl alcohol
dehydrating agent:
slow dehydrating agent producing less shrinkage that hardens less than ethanol
butyl alcohol
dehydrating agent:
not suitable for rapid tissue processing
butyl alcohol
in dehydrating, ___ (descending/ascending) concentrations of alcohol is used
ascending
factors affecting the strength of initial alcohol required in dehydration
size
nature of tissue
fixative used
smaller and more delicate tissues require ___ (higher/lower) concentration and ___ (longer/shorter) intervals between ascending grades of alcohol in dehydration
lower
shorter
the tissue may be stored in ___ alcohol but not for longer periods of time
70-80
prolonged storage in lower concentration of alcohol tends to ___ the tissue, while higher concentration may interfere with the ___ properties
macerate
staining
the dehydration time may be hastened at ___C
37C
serves as an indicator that will accelerate and insure complete dehydration
anhydrous copper sulfate
dehydrating agent:
clear, colorless fluid that mixes with water, ethanol, and most organic solvent
acetone
dehydrating agent:
cheap, rapid-acting dehydrating agent which dehydrates in 1/2 to 2 hours
acetone
T/F: acetone is more miscible with epoxy resins than alcohol
T
dehydrating agent:
an excellent dehydrating and clearing agent that is readily miscible in water, melted paraffin, alcohol, and xylol
dioxane
T/F: one of the major disadvantages of dioxane is that is shrinks that tissue
F (it produces less tissue shrinkage)
dehydrating agent:
tissues may be placed directly into the solution after washing out
dioxane
dehydrating agent:
makes the tissue brittle with prolonged exposure
acetone
T/F: one of the major disadvantages of acetone is that is shrinks that tissue
T
T/F: acetone is not recommended for routine dehydration purposes
T
dehydrating agent:
tissue sections tend to ribbon poorly
dioxane
dehydrating agent:
produces highly toxic vapor
dioxane
dehydrating agent:
should not be used routinely; the laboratory room must be properly ventilated and all residues should be washed down in the sink
dioxane
in this dehydration method, the tissue is wrapped in a gauze bag and suspended in a bottle containing dioxane and a little anhydrous calcium oxide
Weiseberg’s method
in Weiseberg’s method, the dehydration period range is ___
3-24 hrs
in using dioxane as a dehydrating agent, tissues treated with which reagent should be thoroughly washed in running tap water prior to treatment
chromate fixative (Regaud’s or Moller’s fluid)
dehydrating agent:
dehydrates rapidly; may be stored for months without producing hardening or distortion
cellosolve
cellosolve is combustible at what temperature?
110-120F
in using cellosolve, ___-based glycol ether should be used instead of ethylene-based glycol ethers
propylene
dehydrating agent:
removes water very readily and produces very little distortion and hardening
triethyl phosphate
dehydrating agent:
used to dehydrate sections and smears following certain stains
triethyl phosphate
T/F: triethyl phosphate produces minimum shrinkage
T
dehydrating agent:
can also be used for demixing, clearing, and dehydrating paraffin section
tetrahydrofuran (THF)
dehydrating agent:
most staining procedures give improved results
tetrahydrofuran (THF)
for soft tissues like an embryo, the first stage of ___ alcohol is used followed by a graded treatment of the alcohol to prevent tissue shrinkage
50%
tissues fixed in ___ fluid are transferred to 90% alcohol because lower grades of alcohol may cause swelling of the fibrous tissues
Susa
in quality check, a layer of anhydrous copper sulfate should be approximately ___cm thick, should prevent the contamination; alcohol would turn ___ if it gets diluted
2-2.5
blue
dehydrating agent:
causes non-toxic but offensive odor
tetrahydrofuran
