CHAPTER 9: DEHYDRATION Flashcards
This is the process of removing intercellular and extracellular water from the tissue following fixation and prior to wax impregnation
Dehydration
Dehydration is done following what process? and prior to what?
following fixation and prior to wax impregnation
What do you call the solutions utilized to make the dehydration process possible?
Dehydrating agents
What do you call the solutions utilized to make the dehydration process possible?
Dehydrating agents
Many of these dehydrating agents are what?
Alcohols
Alcohols of various types are generally used in increasing strengths to remove what?
to remove aqueous tissue fluids with little disruption caused by diffusion currents
Alcohols of various types are generally used in decreasing strengths to remove aqueous tissue fluids
True or False
False
increasing strengths
Alcohols of various types are generally used in increasing strengths to remove aqueous tissue fluids with little disruption to the tissue caused by what?
caused by diffusion currents
What is the difference between drying and dehydration?
- drying is the removal of water by evaporation from solid, semi-solid or liquid
- dehydration involves slow substitution of the water in the tissue with an organic solvent
This is the removal of water by evaporation from a solid, semi-solid, or liquid
Drying
Drying is the removal of what? by what? from a what?
removal of water by evaporation from a solid, semi-solid, or liquid
This is the slow substitution of the water in the tissue with an organic solvent
Dehydration
Dehydration is the what? in the what? with a/an what?
is the SLOW SUBSTITUTION o f water in the TISSUE with an ORGANIC SOLVENT
Most dehydrating agents are weak organic solvents
True or False
FALSE
strong organic solvents
What do most dehydrating agents that are strong organic solvents bring about?
They bring about some SHRINKAGE and EXTRACTION of cell components
What must be done to minimize the effects (shrinkage and extraction of cell components) of these strong organic solvents?
to minimize these effects, dehydrating agents are used in graded series for short periods of time, and water is gradually replaced
Why must water be gradually replaced in dehydrating agents?
so that violent osmotic changes do not produce distortions
Dehydrating agents are used in graded series for long periods of time
True or False
FALSE
short periods of time
Dehydrating agents are used in a graded series for short periods of time, and water is gradually replaced so that what?
so that violent osmotic changes do not produce distortions
Dehydrating agents are used in a graded series for short periods of time, and water is gradually REPLACED so that violent osmotic changes do not produce what?
distortions
What are the7 characteristics of an IDEAL DEHYDRATING SOLUTION?
- should dehydrate rapidly without producing considerable shrinkage or distortion of tissues
- should be able to dehydrate even fatty tissues
- should not be toxic to the body
- should not be a fire hazard
- should not evaporate very fast
- should not harden tissues excessively
- should not remove stains
An ideal dehydrating solution should dehydrate rapidly without producing what?
without producing considerable shrinkage or distortion of tissues
An ideal dehydrating solution should not be able to dehydrate fatty tissue
True or False
FALSE
should be able to dehydrate even fatty tissues
Ideal dehydrating solutions should be able to remove stains
True or False
False
should not remove stains
Ideal dehydrating solutions should be able to remove stains
True or False
False
should not remove stains
What is the GENERAL rule despite the dehydrating agent used?
the amount in each step should NOT BE LESS THAN 10 times the volume of the tissue
Why must the amount of dehydrating agent not be less than 10 times the volume of the tissue?
to ensure complete penetration of the tissue by the dehydrating solution
The amount in each step in dehydration should be less than 10 times the volume of the tissue
true or false
false
should not be less than 10 times the volume of the tissue
Dehydration time must be kept as long as possible
True or False
False
must be kept as brief as possible
Why must dehydration be kept as brief as possible?
to minimize the risk of extracting cellular constituents
All water miscible, anyhydrous fluid can be used as a dehydrating agent
True or False
FALSE
Almost any water miscible, anhydrous fluid
What are the 6 Commonly Used Dehydrating Agents?
D’CAATT
- Dioxane
- Cellosolve
- Acetone
- Alcohol
- Triethyl phosphate
- Tetrahydrofuran
Among the commonly used dehydrating agents, what is the MOST COMMON?
Alcohol
Ethyl alcohol is also called ….
ethanol
This is the alcohol recommended for routine dehydration of tissues
Ethanol/Ethyl alcohol
Ethyl alcohol is a clear, colorless, flammable fluid
True or False
True
This is considered to be the best dehydrating agent because it is fast-acting, it mxes with water and many organic solvents, and it penetrates tissues easily.
Ethyl alcohol
What makes ethanol the best dehydrating agent?
- it is fast acting
- It mixes with water and many ORGANIC solvents
- It penetrates tissues easily
Ethanol is poisonous and not very expensive
True or False
False
not poisonous
This alcohol is a toxic dehydrating agent
Methyl alcohol
This alcohol is primarily employed for blood and tissue films and for smear preparations
Methyl alcohol
Methyl alcohol is primarily employed for what?
for blood and tissue films and for smear preparations
This alcohol is utilized in plant and animal micro-techniques
Butyl alcohol
Butyl alcohol is utilized in what?
utilized in plant and animal micro-techniques
This [alcohol] is a slow dehydrating agent
Butyl alcohol
Butyl alcohol produces less shrinkage and hardening than ethyl alchol
True or False
True
This is recommended for tissues which do not require rapid processing
Butyl alcohol
Methyl alcohol is recommended for tissues which do not require rapid processing
True or False
FALSE
Butyl alcohol
Methyl alcohol is recommended for tissues which do not require rapid processing
True or False
FALSE
Butyl alcohol
Butyl alcohol is recommended for tissues which do not require what?
do not require rapid processing
It is advisable to transfer fixed tissues directly from water or aqueous fixative directly into absolute ethanol
True or False
False
It is NOT advisable
What happens when you transfer fixed tissues directly from water or aqueous fixative directly into absolute ethanol?
Doing so causes a rapid removal of water which can distort the appearance of more delicate cells and structures.
What happens to the appearance when there is a rapid removal of water due to direct transfer of fied tissues from water or aqueous fixative into absolute ethanol?
the rapid removal of water can distort the appearance of more delicate cells and structures
What is advised to avoid the distortion of the appearance of of more delicate cells and structures?
It is advisable to remove water gently and allow the tissue to SLOWLY adjust to its removal
The more delicate the tissue, the more gently this [the removal of water] should be done
True or false
True
There is no hard and fast rule
True or False
True
In most instances, dehydration starts by placing the fixed specimen in what concentration of ethyl alcohol in water?
starts by placing the fixed specimen in 70% ethyl alcohol in water
After placing the fixed specimen in 70% ethyl alcohol, the concentration progresses to what percent?
progressing through 95% ethyl alcohol
After placing the fixed specimen in 95% ethyl alcohol, fixed specimen should, then, be placed in what percent of ethyl alcohol?
100% ethyl alcohol
In most instances, what are the increasing concentrations used?
70%, 95%, 100%
In most instances, what are the increasing concentrations used?
70%, 95%, 100%
For delicate tissues, particularly embryonic tissues, it is recommended that dehydration start with what concentration?
30% ethanol
30% ethanol is recommended for dehydrating what kind of tissues?
for delicate tissues, particularly embryonic tissues
Under no circumstances shoudla formalin-fixed tissue be trasnferred directly to higher grades of alcohol, e.g. 85-95%
True or False
True
Why must under no circumstanes should a formalin-fixed tissue be transferred directly to higher grades of alcohol?
because this is liable to produce considerable shrinkage and hardening of tissues leading to distortion
The direct transferring of formalin-fied tissues to higher grades of alcohol should not be done beause this is liable to produce considerable shrinkage and hardening of tissues leading to what?
leading to distortion
What percent are concentrated alcohols at?
95% or absolute
These alcohols tend to harden only the surface of the tissue while deeper parts are not completely penetrated
Concentrated alcohol (95% or absolute)
Why do we not use concentrated alcohols in dehydration?
Because concentrated alcohols tend to harden only the surface of the tissue while deeper parts are not completely penetrated
The hardening of only the surface of the tissue while the deeper parts are not completely penetrated will result in the what?
this will result in a RELATIVELY UNEQUAL IMPREGNATION of tissue with consequently poor cutting of sections
This will result in a relatively unequal impregnation of tissue
concentrated alcohols
The unequal impregnation of tissue will consquenty cause what?
poor cutting of sections
What must be done to avoid the unequal impregnation of tissue and poor cutting of sections?
70% or lower concetrations of alcohol, gradually increased to 95%, are used
What must be done to avoid the unequal impregnation of tissue and poor cutting of sections?
70% or lower concetrations of alcohol, gradually increased to 95%, are used
The strength of initial alcohol requiured in each concentration will depend upon the size, nature of each tissue, and fixative used
True or False
True
The strength of initial alcohol requiured in each concentration will depend upon what?
the size, nature of each tissue, and fixative used
Larger and less delicate tissues require lower concentrations and shorter intervals between changes of succeeding ascending grades of alcohol
True or False
False
Smaller and more delicate tissues
Larger and less delicate tissues require lower concentrations and shorter intervals between changes of succeeding ascending grades of alcohol
True or False
False
Smaller and more delicate tissues
What is required for smaller and more delicate tissues?
Lower concentrations and shorter intervals between changes of succeeding ascending grades of alcohol
80% is considered a very concentrated solution
True or False
True
A very concentrated solution makes tissues hard, brittle, and difficult to cut
True or false
True
A very concentrated solution (above 80%) makes tissues hard, brittle, and difficult to cut.
True or False
TRUE
Prolonged storage in lower concentrations of alcohol (below 70%) tends to macerate the tissue
True or false
TRUE
The tissue may be stored in 70-80% alcohol, although not for very long periods of time, since this may later interfere with the staining properties of the specimen
True or false
TRUE
After dehydration in 100% ethanol, it is now possible to proceed straight to wax embedding
True or false
FALSE
it is not possible to proceed straight to wax embedding
After dehydration in 100% ethanol, it is now possible to proceed straight to wax embedding
True or false
FALSE
it is not possible to proceed straight to wax embedding
Why is it not possible to proceed straight to wax embedding?
because ethanol and wax DO NOT MIX
This term refers to the property of the solvents used
clearing
This is when the tissues have a relatively high refractive index and when tissue is immersed in them
clearing
what happens to tissues when they undergo clearing?
the tissue becomes transparent and clear
For tissue preparation, two to three hours in each solution should be adequate
True or False
FALSE
one to two
For tissue preparation, two to three hours in each solution should be adequate
True or False
FALSE
one to two
Tissues with a high water content such as embryo tissue would require a much shorter time
True or False
TRUE
What is an example of a tissue with a high water content?
embryo tissue
How can we ensure the complete removal of water during dehydration?
Use at least two changes of 100% ethanol of at least one half hour each
To ensure complete removal of water during dehydration, use at least two changes of 100% ethanol of at least one hour each
True or False
False
at least one half hour each
To ensure complete removal of water during dehydration, use at least two changes of 100% ethanol of at least one hour each
True or False
False
at least one half hour each
Never leave tissues in 95 or 100% ethanol more than a total of how many hours?
2 hours
What will happen to the tissues if left in 95 or 100% ethanol more than a total of 2 hours?
the tissues will harden
Tissues can be stored in 95% ethanol at any time during an interruption in the routine
True or False
False
70% ethanol
A temperature of what will hasten dehydration time
37C
This is the temperature wherein it is especially used for tissue sections that require urgent examinations such as fragmentary biopsies
37C
This is the temperature wherein it is especially used for tissue sections that require urgent examinations such as fragmentary biopsies
37C
Ti ensure complete dehydration, what is placed in the bottom of the container?
A layer of anhydrous copper sulfate is placed in the bottom of the container
How many inches deep must the layer of anhydrous copper sulfate be?
1/4 inch deep
The layer of anhydrous copper sulfate is covered with what?
covered with filter paper
What is the purpose of the layer of anhydrous copper sulfate?
- to ensure complete dehydration
- will accelerate dehydration
The layer of anhydrous copper sulfate will accelerate dehydration by what?
by removing water from the dehydrating fluid
This will indicate full saturation of dehydrating fluids with water
A blue discoloration of copper sulfate crystals
A blue discoloration of copper sulfate crystals will indicate what?
a full saturation of dehydrating fluids with water
what is the color of the discoloration of copper sulfate crystals will indicate full saturation of dehydrating fluids with water
A blue discoloration
After a layer of anhydrous copper sulfate is placed in the bottom of the container and covered with filter paper, alcohol is then discarded and changed with what?
changed with a fresh solution
What is the boiling point of ethanol (ethyl alcohol)?
78.3C
What are the 9 advantages of ethanol?
ILMNR CAN STILL APPEAR FAST
- Inexpensive and easily obtained
- Little shrinkage if graded alcohols are used
- Miscible in all proportions with water
- Nontoxic
- Reliable
- Can be used on eyes and embryos, if graded alcohols are used
- Still considered best dehydrating solution
- Appears to cause less extract of cellular components in general than other agents
- Fast acting
What are the 9 disadvantages of ethanol?
EEELMMMMO
- Expensive
- Extracts methylene blue and other thiazine dyes from sections
- Extracts more lipids than acetone
- Long periods in absolute ethanol will cause excessive shrinkage
- may be difficult to obtain
- may cause more shrinkage of specimen
- may react with an unreduced OsO4 remaining in specimen
- may have prohibitive taxes that necessitate troublesome bookkeeping
- Only slightly miscible with most resins
Long periods in absolute ethanol will cause what?
will cause excessive shrinkage and hardening
What is the boiling point of butanol (Butyl alcohol) ?
117.7C
What are the advantages of Butanol?
ELbutanolM (LBM)
- Excellent for slow processing
- Less shrinkage and hardening than with ethyl
- Miscible with paraffin
What are the disadvantages of butyl alcohol?
LODS
- Long periods of infiltration necessary
- Odorous
- Dehydrating power low
- Slow-acting
What is the boiling point of tertiary butanol (butyl alcohol)?
82.8C
This acts as dehydrating and clearing agent in tertiary butanol
Universal solvent
What are the advantages of tertiary butanol?
MUM
- May be used in staining series as a dehydrating agent
- Universal solvent
- Mixes withh water, ethanol, xylene, and paraffin in all
This alcohol mixes with water, ethanol, xylene, and paraffin in all
Tertiary butanol (Butyl alcohol)
What are the disadvantages of tertiary butanol?
PROM
- Primary infiltration must be done in half tertiary butanol and half paraffin, prior to paraffin impregnation
- Reagent tends to solidify at room temperature or below 25C
- Odorous
- More expensive than butanol
This alcohol is more expensive than butanol
Tertiary butanol
With this alcohol, the reagent tends to solidify at room temperature of below 25C
Tertiary butanol
With tertiary butanol, the reagent tends to solidify at what temperature?
solidify at room temperature or below 25C
What is the boiling point for isopropanol (isopropyl alcohol)?
82.3C
What are the advantages of isopropanol?
LLLENS
- Less expensive than tax-free alcohol
- Lillie considers it “the best all-around substitute for ethyl alcohol
- Less shrinkage and hardening than ethanol
- Excellent substitute for ethanol
- No government restrictions on its use
- Sufficiently water-free to use in place of absolute ethanol
This is the alcohol wherein Lillie considers it “the best all-around substitute for ethyl alcohol”
Isopropanol
Lillie considers isopropanol as what?
“the best all-around substitute for ethyl alcohol”
What are the disadvanatges of isopropanol?
Cannot Cannot
- cannot be used in the celloidin technic since nitrocellulose is insoluble in it
- cannot be used for preparing staining solutions, since dyes are not soluble in it
Why can isopropanol cannot be used in the celloidin technic?
since nitrocellulose is insoluble in isopropanol
Why can isopropanol cannot be used for preparing staining solutions?
since dyes are not soluble in it
What is the boiling point of pentanol?
128C
Pentanol is also known as …
amyl alcohol
What are th advantages of pentanol?
MD
- Miscible with 90% alcohol, toluene and xylene
- Dissolves paraffin wax
What are the disadvanatages of pentanol?
CNT
- Cannot be used in poorly ventilated rooms
- Not miscible with water
- Toxic
What is the boiling point of acetone?
56C
Acetone is cheap and is a rapid-acting dehydrating agent
True or False
True
Acetone is utilized for what?
Utilized for most urgent biopsies
Acetone dehydrates in 1/2 to 2 hours
True or False
TRUE
Acetone is a clear, colorless fluid that does not mix with water, ethanol and most organic solvents
True or False
FALSE
does mix with water, ethanol, and most oranic solvents
Acetone is a clear, colorless fluid that does not mix with water, ethanol and most organic solvents
True or False
FALSE
does mix with water, ethanol, and most oranic solvents
Acetone is more miscible with epoxy resins than alcohol
True or False
True
Acetone is highly flammable and requires considerable care in handling
True or False
TRUE
Acetone is rapid in action but penetrates tissues poorly
True or false
True
Acetone causes brittleness in tissue that are placed in acetone for prolonged period of time
True or False
True
What happens when a tissue is placed in acetone for a prolonged period of time?
it causes brittleness in tissues
Most lipids are removed from tissues with what dehydrating agent?
Acetone
The use of this dehydrating agent has been limited only to small pieces of tissues
Acetone
Why is acetone only limited to small pieces of tissues?
due to its extreme volatility and inflammability
Why is acetone not recommended for routine dehydration purposes?
Because of considerable tissue shrinkage produced
Acetone is recommended for routine dehydration purposes
True or False
FALSE
not recommended for routine dehydration
What are the advantages of acetone?
LMMNOP -> LMMDR (D looks like O, R looks like P)
- Less expensive than ethanol
- May cause less shrinkage of specimen than ethanol
- Miscible with most embedding resins
- Not reactive wih OsO4, remaining in specimen
- Does not extract methylene blue and other dyes from stained sections
- Rapid dehydrating agent
What are the disadvantages of acetone?
Requires Volume Best Needs Absolute Uranyl Evaporates Flammable
- Requires a clearing agent
- Volume must be 20 times that of the tissue
- Best processing requires a graded series of a mixture of acetone and xylene before one can go into paraffin
- Needs good ventilation
- Absolute acetone is easily contaminated with water, resulting in complete dehydration
- Uranyl acetate and phosphotungstic acid are only soluble in dilute solutions of acetone
- Evaporates rapidly
- Flammable
This is easily contaminated with water, resulting in complete dehydration
Absolute acetone
Absolute acetone is easily contaminated with what?, resulting in what?
contaminated with water, resulting in complete dehydration
These are only soluble in dilute solutions of acetone
- Uranyl acetate
- phosphotungstic acid
Uranyl acetatae and phosphotungstic acid are only soluble in what?
only soluble in dilute solutions of acetone
Dioxane is also known as …
Diethylene dioxide
Diethylene dioxide is also knwon as …
Dioxane
This is an excllent dehydrating and clearing agent readily miscible in water, melted paraffin, alcohol, and xylol
Dioxane
Dioxane has a double purpose. It is excellent for what processes?
excellent for dehydrating and clearing agent
Dioxane is readily miscible in what solvents?
readily miscible in water, melted paraffin, alcohol, and xylol
Dioxane produces less tissue shrinkage as compared to what?
as compared to alcohol dehydration
Can tissues be left in dioxane for long periods of time?
Yes or no
Yes
Tissues can be left in this reagent for long periods of time without affecting the consistency or staining properties of the specimen
What reagent?
Dioxane
What is the refractive index of dioxane?
1.42
What is the boiling point of dioxane?
101.5C
In dioxane, tissues may be placed DIRECTLY into the solution after washing out because?
because dioxane is miscible with both water and paraffin
Because dioxane is miscible with water and paraffinx, tissues may be placed directly into the solution after washing out
True or False
True
Tissues sections dehydrated with dioxane tend to ribbon poorly
True or False
True
Aside from being expensive, what is the main disadvantage of dioxane?
Dioxane is also extremely dangerous
The vapor of dioxane produes a cumulative and highly toxic action in man
True or False
True
Dioxane can be used routinely
True or FALSE
False
should not be used routinely
Why should dioxane not be used as as routine for dehydration?
Because its vapor produces a cumulative and highly toxic action in man
The laboratory room should be properly ventilated when using dioxane
True or False
True
What must be done with the residues in using dioxane?
all residues should be washed down in the sink
Why should dioxane not be recycled?
as the risk of creating explosive peroxides increases greatly
What are the two methods in using dioxane?
- Graupner’s method
- Weiseberger’s method
What is the process in the Graupner’s method?
- Pure dioxane solution for 1 hour
- Pure dioxane solution for 1 hour
- Pure dioxane solution for 1 hour
- paraffin wax for 15 mins
- paraffin wax for 45 mins
- paraffin wax for 2 hours
- Embed in mold and cool in water
This is the method wherein the tissue is wrapped in a gauze bag and suspended in a bottle containing dioxane and a little anhydrous calcium oxide.
Weiseberger’s method
What is the process in the Weiseberger’s method?
Wrap tissue in a gauze bag and suspend in a bottle containing dioxane and a little anhydrous calcium oxide.
In the Weiseberger’s method, water is displaced by dioxane and in turn absorbed by what?
absorbed by calcium oxide or quicklime
The dehydration period in the Weiseberger’s method ranges from 5-24 hours.
True or False
FALSE
3-24 hours
The dehydration period in the Weiseberger’s method ranges from 5-24 hours.
True or False
FALSE
3-24 hours
What are the advanatages of dioxane?
DUMF
- Does not harm tissue over long periods of time
- Universal solvent - it dehydrates and clears
- Miscible with walter, alcohol, xylene, and paraffin
- Faster dehydrant than ethanol
This dehydrating agent is a faster dehydrant than ethanol
dioxane
What are the disadvanatages of dioxane?
NO CDC
- Needs large volume for dehydration
- Odorous
- Costs about fo(u)r times more than absolute alcohol
- Distorts tissue-containing cavities
- Cumulatively toxic
Cellosolve is also called …
ethylene glycol monoethyl ether
Ethylene glycol monoethyl ether is also called …
Cellosolve
What is the boiling point for ethylene glycol monoethyl ether?
156.4C
Cellosolve does not dehydrate rapidly
Trie or False
False
dehydrates rapidly
Cellosolve does not dehydrate rapidly
Trie or False
False
dehydrates rapidly
With cellosolve, the tissue may be transferred from water or normal saline DIRECTLY to cellosolve
True or False
TRUE
Tissue can be stored in cellosolve for months without producing hardening or distortion
True or False
TRUE
What is the caution in using ethylene glycol monoethyl ether?
Cellosolve is combustible at 110-120F and are toxic by inhalation, skin contact, and ingestion
Cellosolve is combustible at what temperautre?
110-120F
Cellosolve is toxic by what?
- inhalation
- skin contact
- ingestion
Following exposure, what in particular are vulnerable to the toxic side effects of cellosolve?
the reproductive, fetal, urinary, and blood systems
What should be used instead of ethylene-based glycol ethers, if it cannot be avoided?
propylene-based glycol ethers
What are the advanatages of cellosolve?
RAT
- Rapid dehydrating agent
- Avoids distortion and does not require graded dilutions
- Tissue may remain in it for months without injury
What are the disadvanatges of cellosolve?
ERR
- Expensive
- Rapidly absorbs water from the air
- Requires clearing agent
What is the boiling point of triethyl phosphate?
215 C
What happens when tissues are fixed, washed and transferred DIRECTLY into triethyl phosphate solution for dehydration?
It removes water very readilyand produces very little distortion and hardneing of tissue
Triethyl phosphate is soluble in what?
- Water
- ether
- benzene
- chloroform
- acetone
- xylene
Triethyl phosphate produces minimum shrinkage
true or false
TRUE
Triethyl phosphate is used to dehydrate sections and smears following certain stains
True or False
TRUE
What are the advanatages of triethyl phosphate?
DDMMS
- Does not harden tissue excessively
- Displaces water readily with slight distortion
- May be used as a dehydrating solution in the staining sequence
- May be used in routine paraffin technic
- Soluble in alcohols, benzene, toluene, xylene, ether, chloroform
This dehydrating agent may be used in routine paraffin technique
triethyl phosphate
This dehydrating agent may be used as a dehydrating solution in the staining sequence
triethyl phosphate
what are the disadvantages of triethyl phosphate?
NONE
This dehydrating agent has no disadvantages
triethyl phosphate
THF is a reagent that both dehydrates and clears tissues since it is miscible in both water and paraffin
True or False
TRUE
Tetrahydrofuran is a reagent that both dehydrates and clears tissues
True or False
TRUE
THF is miscible in water but not in paraffin
True or False
FALSE
THF is miscible in both water and paraffin
This dehydrating agent can dissolve many substances including fats
THF
THF is in itself miscible with lower alcohols, ether, chloroform, acetone, benzene, and xylene
True or False
TRUE
This dehydrating agent may be used for demixing, clearing, and dehydrating paraffin sections befoe and after staining
THF
THF may be used for demixing, clearing, and dehydrating paraffin sections only after staining
true or false
FALSE
before and after staining
THF may be used for demixing, clearing, and dehydrating paraffin sections only after staining
true or false
FALSE
before and after staining
THF causes less shrinkage and easier cutting of sections with fewer artifacts
True or False
TRUE
THF does not dissolve out aniline dyes
true or false
true
It is a fact that most staining procedures give improved results with THF
True or false
true
THF is toxic if inhalaed or ingested
True or false
TRUE
The vapor from THF causes what?
- nausea
- dizzinessheadache
- anesthesia
It is an eye and skin irritant
THF
Prolonged exposure in this dehydrating agent may cause conjunctival irritation
THF
Prolonged exposure of up to how many months, can THF cause conjunctival irritation?
up to 6 months
Prolonged exposure (up to 6 months) to THF can cause what?
conjunctival irritation
Why should processing with THF be done in a well-ventilaed room?
because of its offensive odor and its vapor
What can be gloves can be suitable when using THF?
Teflon gloves
The use of triethyl phosphte should be avoided if possible, as there is no practical way to absolutely protect skin against contact
True or false
FALSE
THF
What are the advanatages of THF?
Solvents Better Not LRM
- Solvents of mounting media
- Better results than most universal solvents
- NOT TOXIC
- Low toxicity; low fire and explosion hazard
- Rapid without excessive shrinkage and hardening
- Miscible in all proportions with water, ether, chloroform, acetone, and the hydrocarbons xylene, toluene, and benzene
What are the disadvantages of THF?
DEO
- Dyes are not soluble in tetrahydrofuran
- Evaporates rapidly
- Odorous - should be used in well-ventilated room
Tissues processing for what is commonly accomplished using ethanol as a dehydrating solvent and propylene oxide a transition fluid?
Transmission electron microscopy (TEM)
WHAT IS USED AS A DEHYDRATING SOLVENT IN TISSUE PROCESSING FORTEM?
ethanol
Propylene oxide is used as a what in tissue processing for TEM?
propylene oxide is used as a transition fluid
What are the undesirable properties of ethanol [in TEM]?
- ethanol solubilizes lipids
What are the undesirable properties of ethanol [in TEM]?
- ethanol solubilizes lipids
What are the undesirable properties of propylene oxide [in TEM]?
propylene oxide is
- completely miscible with embedding resins
- it can infiltrate tissues readily
- reduce viscosity of embedding resin mixtures
Propylene oxide can infiltrate tissues readily and reduce the viscosity of embedding resin mixtures because of what?
becuase of its low viscosity
Propylene oxide is highly flammable, volatile, toxic, and potentially carcinogenic
True or False
TRUE
It is very reactive even at low temperatures
Propylene oxide
It may combine with reactive groups in cells
Propylene oxide
Propylene oxide may cause certain cytochemical and staining reactions
True or False
TRUE
It may react with epoxy groups and partially inhibit polymerization which adversely affects hardness and cutting properties of blocks
Propylene oxide
This is a good substitute for propylene oxide
Acetonitrile
Acetonitrile is a good substitute for what?
for propylene oxide
It is reported to be non-carcinogenic, less toxic and not as flammable as propylene oxide
Acetonitrile
Acetonitrile is freely miscible with water, alcohols, acetone, and epoxy resins
True or false
TRUE
Acetonitrile interferes with epoxy polymerization
True or false
FALSE
does not interfere
The resulting cured resins from aceonitrile have excellent cutting quality and beam stability
True or false
True
This is an excellent dehydrating agent whose use does not necessitate modification of current techniques
Acetonitrile
The high solubility of phospholipids in acetonitrile limits the loss of membrane lipids
True or false
FALSE
low solubility
The low solubility of phospholipids in acetonitrile limits the loss of membrane lpids which leads to what?
leads to a better preservation of tissue features
Acetonitrile is a dehydrating agent for cells prepared for WHAT?
prepared for Scanning Electron Microscopy (SEM)
It is used as a dehydrating agent for cells prepared for Scanning Electron Microscopy (SEM)
Acetonitrile
