CHAPTER 9 DEHYDRATION Flashcards by Arriane Cyrel (MTI) | Brainscape

Q

process of removing intercellular and extracellular water from the tissue following fixation and prior to wax impregnation

A

DEHYDRATION

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Q

Solutions used for DEHYDRATION

A

Dehydrating Agents

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Q

is the removal of water by evaporation from a solid, semi-solid or liquid.

A

Drying

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Q

should NEVER be allowed to air dry.

A

Solid tissues

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Q

involves slow substitution of the water in the tissue with an organic solvent.

A

Dehydration

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Q

As a general rule, whatever dehydrating agent is used, the amount in each step should not be [?] the volume of the tissue in order to ensure complete penetration of the tissue by the dehydrating solution.

A

less than 10 times

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Q

Commonly Used Dehydrating Agents Are:

A

Alcohol (most common)
Acetone
Dioxane
Cellosolve
Triethyl phosphate
Tetrahydrofuran

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Q

is the alcohol recommended for routine dehydration
of tissues.

A

Ethyl alcohol (ethanol)

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Q

It is a clear, colorless, flammable fluid.

A

Ethyl alcohol (ethanol)

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Q

It is considered to be the best dehydrating agent because it is fast-acting, it mixes with water and many organic solvents, and it penetrates tissues easily.

A

Ethyl alcohol (ethanol)

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Q

It is not poisonous and not very expensive.

A

Ethyl alcohol (ethanol)

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Q

is a toxic dehydrating agent, primarily employed for blood and tissue films and for smear preparations.

A

Methyl alcohol

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Q

utilized in plant and animal micro-techniques

A

Butyl alcohol

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Q

is a slow dehydrating agent, producing less shrinkage and hardening than ethyl alcohol and is recommended for tissues which do not require rapid processing.

A

Butyl alcohol

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Q

At this point all but a tiny residue of tightly bound (molecular) water should have been removed from the specimen. A typical dehydration sequence for specimens not more than 4mm thick would be:

A

70% ethanol 15 min
90% ethanol 15 min
100% ethanol 15 min
100% ethanol 15 min
100% ethanol 30 min
100% ethanol 45 min

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Q

A temperature of [?] will hasten dehydration time and is especially used for tissue sections that require urgent examinations such as fragmentary biopsies.

A

37°C

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Q

To insure complete dehydration, a layer of anhydrous copper sulfate, about[?] deep is placed in the bottom of the container and covered with filter paper. This will accelerate dehydration by removing water from the dehydrating fluid.

A

1/4 inch

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Q

A [?] of copper sulfate crystals will indicate full saturation of dehydrating fluids with water. Alcohol is then discarded and changed with a fresh solution.

A

blue discoloration

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Q

Nontoxic

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Miscible in all proportions with water

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Little shrinkage if graded alcohols are used

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Can be used on eyes and embryos, if graded alcohols are used

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Fast acting

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Still considered best dehydrating solution

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Reliable

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Appears to cause less extraction of cellular components in general than other agents

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Inexpensive and easily obtained

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Expensive

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Long periods i n absolute ethanol will cause excessive shrinkage and hardening

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

May be difficult to obtain

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

May have prohibitive taxes that necessitate troublesome book-keeping

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Extracts methylene blue and other thiazine dyes from sections

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Extracts more lipids than acetone

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

May cause more shrinkage of specimen

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

May react with an unreduced 0s04 remaining in specimen

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Only slightly miscible with most resins

A

Ethanol (ethyl alcohol) Boiling point 78.3° C

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Q

Less shrinkage and hardening than with ethyl

A

Butanol (butyl alcohol) Boiling point 117.7° C

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Q

Excellent for slow processing

A

Butanol (butyl alcohol) Boiling point 117.7° C

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Q

Miscible with paraffin

A

Butanol (butyl alcohol) Boiling point 117.7° C

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Q

Odorous

A

Butanol (butyl alcohol) Boiling point 117.7° C

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Q

Slow-acting

A

Butanol (butyl alcohol) Boiling point 117.7° C

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Q

Long periods of infiltration necessary

A

Butanol (butyl alcohol) Boiling point 117.7° C

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Q

Dehydrating power low

A

Butanol (butyl alcohol) Boiling point 117.7° C

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Q

Universal solvent—acts as dehydrating and clearing agent

A

Tertiary butanol (butyl alcohol) Boiling point 82.8° C

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Q

May be used in staining series as a dehydrating agent

A

Tertiary butanol (butyl alcohol) Boiling point 82.8° C

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Q

Mixes with water, ethanol, xylene, and paraffin in all

A

Tertiary butanol (butyl alcohol) Boiling point 82.8° C

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Q

Odorous

A

Tertiary butanol (butyl alcohol) Boiling point 82.8° C

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Q

More expensive than butanol

A

Tertiary butanol (butyl alcohol) Boiling point 82.8° C

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Q

Primary infiltration must be done in half tertiary butanol and half paraffin, prior to paraffin impregnation

A

Tertiary butanol (butyl alcohol) Boiling point 82.8° C

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Q

Reagent tends to solidify at room temperature or below 25° C

A

Tertiary butanol (butyl alcohol) Boiling point 82.8° C

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Q

Excellent substitute for ethanol

A

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Q

Less shrinkage and hardening than ethanol

A

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Q

No government restrictions on its use

A

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Q

Sufficiently water-free to use in place of absolute ethanol

A

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Q

Lillie considers it “the best all- around substitute for ethyl alcohol”

A

Isopropanol (isopropyl alcohol) Boiling point 82.3° C

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Q

Less expensive than tax-free alcohol

A

Isopropanol (isopropyl alcohol) Boiling point 82.3° C

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Q

Cannot be used in the celloidin technic since nitrocellulose is insoluble in it

A

Isopropanol (isopropyl alcohol) Boiling point 82.3° C

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Q

Cannot be used for preparing staining solutions, since dyes are not soluble in it

A

Isopropanol (isopropyl alcohol) Boiling point 82.3° C

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Q

Miscible with 90% alcohol, toluene and xylene

A

Pentanol (amyl alcohol) Boiling point 128° C

Q

Dissolves paraffin wax

A

Pentanol (amyl alcohol) Boiling point 128° C

Q

Toxic

A

Pentanol (amyl alcohol) Boiling point 128° C

Q

Cannot be used in poorly ventilated rooms

A

Pentanol (amyl alcohol) Boiling point 128° C

Q

Not miscible with water

A

Pentanol (amyl alcohol) Boiling point 128° C

Q

is a cheap, rapid-acting dehydrating agent utilized for most urgent biopsies which it dehydrates in 1/2 to 2 hours

A

ACETONE (Boiling point 56° C)

Q

is a clear, colorless fluid that mixes with water, ethanol and most organic solvents

A

ACETONE (Boiling point 56° C)

Q

is more miscible with epoxy resins than alcohol, but is highly flammable and requires considerable care in handling.

A

ACETONE (Boiling point 56° C)

Q

It is rapid in action but penetrates tissues poorly and causes brittleness in tissues that are placed in acetone for prolonged period of time.

A

ACETONE (Boiling point 56° C)

Q

Most lipids are removed from tissues with this dehydrating agent.

A

ACETONE (Boiling point 56° C)

Q

Its use has been limited only to small pieces of tissues due to its extreme volatility and inflammability.

A

ACETONE (Boiling point 56° C)

Q

Because of considerable tissue shrinkage produced, it is not recommended for routine dehydration purposes.

A

ACETONE (Boiling point 56° C)

Q

Rapid dehydrating agent

A

ACETONE (Boiling point 56° C)

Q

Less expensive than ethanol

A

ACETONE (Boiling point 56° C)

Q

Does not extract methylene blue and other dyes from stained sections

A

ACETONE (Boiling point 56° C)

Q

May cause less shrinkage of specimen than ethanol

A

ACETONE (Boiling point 56° C)

Q

Not reactive with 0s04 remaining in specimen.

A

ACETONE (Boiling point 56° C)

Q

Miscible with most embedding resins.

A

ACETONE (Boiling point 56° C)

Q

Requires a clearing agent

A

ACETONE (Boiling point 56° C)

Q

Volume must be 20 times that of the tissue

A

ACETONE (Boiling point 56° C)

Q

Best processing requires a graded series of a mixture of acetone and xylene before one can go into paraffin

A

ACETONE (Boiling point 56° C)

Q

Needs good ventilation

A

ACETONE (Boiling point 56° C)

Q

Evaporates rapidly

A

ACETONE (Boiling point 56° C)

Q

Flammable

A

ACETONE (Boiling point 56° C)

Q

Absolute acetone is easily contaminated with water, resulting in complete dehydration.

A

ACETONE (Boiling point 56° C)

Q

Uranyl acetate and phosphotungstic acid are only soluble in dilute solutions of acetone.

A

ACETONE (Boiling point 56° C)

Q

is an excellent dehydrating and clearing agent readily miscible in water, melted paraffin, alcohol and xylol.

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

It produces less tissue shrinkage as compared to alcohol dehydration.

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Tissues can be left in this reagent for long periods of time without affecting the consistency or staining properties of the specimen.

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Because it is miscible with both water and paraffin, tissues may be placed directly into the solution after washing out. However, tissue sections dehydrated with it tend to ribbon poorly.

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Aside from being expensive, it is also extremely dangerous, and this is its main disadvantage. Its vapor produces a cumulative and highly toxic action in man; hence, it should not be used routinely. The laboratory room should be properly ventilated, and all residues should be washed down in the sink. It should not be recycled as the risk of creating explosive peroxides increases greatly.

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Universal solvent—it dehydrates and clears

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Miscible with water, alcohol, xylene, and paraffin

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Does not harm tissue over long time periods

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Faster dehydrant than ethanol

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Needs large volume for dehydration

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Costs about for times more than does absolute alcohol

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Must be used in well-ventilated rooms

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Cumulatively toxic

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Odorous

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

Distorts tissue-containing cavities

A

DIOXANE (Diethylene Dioxide) Refractive index 1.42; Boiling point 101.5° C

Q

This dehydrates rapidly. The tissue may be transferred from water or normal saline directly to it and stored in it for months without producing hardening or distortion.

A

CELLOSOLVE (Ethylene glycol monoethyl ether) Boiling point 156.4° C

Q

CAUTION: Ethylene glycol ethers are combustible at [?] and are toxic by inhalation, skin contact and ingestion. Following exposure, the reproductive, fetal, urinary and blood systems are particularly vulnerable to their toxic side effects. If it cannot be avoided, propylene-based glycol ethers should be used instead of ethylene-based glycol ethers.

A

110-120°F

Q

Rapid dehydrating agent

A

CELLOSOLVE (Ethylene glycol monoethyl ether) Boiling point 156.4° C

Q

Tissue may remain in it for months without injury

A

CELLOSOLVE (Ethylene glycol monoethyl ether) Boiling point 156.4° C

Q

Avoids distortion and does not require graded dilutions

A

CELLOSOLVE (Ethylene glycol monoethyl ether) Boiling point 156.4° C

Q

Expensive

A

CELLOSOLVE (Ethylene glycol monoethyl ether) Boiling point 156.4° C

Q

Rapidly absorbs water from the air

A

CELLOSOLVE (Ethylene glycol monoethyl ether) Boiling point 156.4° C

Q

Requires clearing agent

A

CELLOSOLVE (Ethylene glycol monoethyl ether) Boiling point 156.4° C

Q

it removes water very readily and produces very little distortion and hardening of tissue.

A

TRIETHYLPHOSPHATE- Boiling point 215° C

Q

It is soluble in alcohol, water, ether, benzene, chloroform, acetone and xylene.

A

TRIETHYLPHOSPHATE- Boiling point 215° C

Q

It is used to dehydrate sections and smears following certain stains and produces minimum shrinkage.

A

TRIETHYLPHOSPHATE- Boiling point 215° C

Q

May be used in routine paraffin technic

A

TRIETHYLPHOSPHATE- Boiling point 215° C

Q

Displaces water readily with slight distortion

A

TRIETHYLPHOSPHATE- Boiling point 215° C

Q

Does not harden tissue excessively

A

TRIETHYLPHOSPHATE- Boiling point 215° C

Q

May be used as a dehydrating solution in the staining sequence

A

TRIETHYLPHOSPHATE- Boiling point 215° C

Q

Soluble in alcohols, benzene, toluene, xylene, ether, chloroform

A

TRIETHYLPHOSPHATE- Boiling point 215° C

Q

Disadvantages: None

A

TRIETHYLPHOSPHATE- Boiling point 215° C

Q

is a reagent that both dehydrates and clears tissues
since it is miscible in both water and paraffin.

A

TETRAHYDOFURAN (THF)

Q

It can dissolve many substances including fats and is in itself miscible with lower alcohols, ether, chloroform, acetone, benzene and xylene.

A

TETRAHYDOFURAN (THF)

Q

It may be used for demixing, clearing and dehydrating paraffin sections before and after staining.

A

TETRAHYDOFURAN (THF)

Q

It causes less shrinkage and easier cutting of sections with fewer artifacts. In fact, most staining procedures give improved results with tetrahydrofuran.

A

TETRAHYDOFURAN (THF)

Q

is toxic if ingested or inhaled.

A

TETRAHYDOFURAN (THF)

Q

Vapors cause nausea, dizziness, headache and anesthesia.

A

TETRAHYDOFURAN (THF)

Q

It is an eye and skin irritant, and prolonged exposure (up to 6 months) may cause conjunctival irritation.

A

TETRAHYDOFURAN (THF)

Q

Miscible in all proportions with water, ether, chloroform, acetone, and the hydrocarbons xylene, toluene, and benzene

A

TETRAHYDOFURAN (THF)

Q

Rapid without excessive shrinkage and hardening

A

TETRAHYDOFURAN (THF)

Q

Low toxicity; low fire and explosion hazard

A

TETRAHYDOFURAN (THF)

Q

Not toxic

A

TETRAHYDOFURAN (THF)

Q

Better results than most universal solvents

A

TETRAHYDOFURAN (THF)

Q

Solvents of mounting media

A

TETRAHYDOFURAN (THF)

Q

Odorous- should be used in well-ventilated room

A

TETRAHYDOFURAN (THF)

Q

Evaporates rapidly

A

TETRAHYDOFURAN (THF)

Q

Dyes are not soluble in tetrahydrofuran

A

TETRAHYDOFURAN (THF)

Q

Tissue processing for transmission electron microscopy (TEM) is commonly accomplished using [?] as a dehydrating solvent and [?] as a transition fluid.

A

ethanol

propylene oxide

Q

solubilizes lipids

A

ethanol

Q

is completely miscible with embedding resins and, because of its low viscosity, it can infiltrate tissues readily and reduce the viscosity of embedding resin mixtures

A

propylene oxide

Q

is a good substitute for propylene oxide. It is reported to be non-carcinogenic, less toxic and not as flammable as propylene oxide.

A

Acetonitrile

Q

It is freely miscible with water, alcohols, acetone, and epoxy resins.

A

Acetonitrile

Q

It does not interfere with epoxy polymerization; and the resulting cured resins have excellent cutting quality and beam stability.

A

Acetonitrile

Q

is also an excellent dehydrating agent whose use does not necessitate modification of current techniques.

A

Acetonitrile

Q

the low solubility of phospholipids limits the loss of membrane lipids and, hence, leads to a better preservation of tissue features

A

Acetonitrile

Q

It is also used as a dehydrating agent for cells prepared for Scanning Electron Microscopy (SEM).

A

Acetonitrile

Q

is the process whereby alcohol or a dehydrating agent is removed from the tissue and replaced with a substance that will dissolve the wax with which the tissue is to be impregnated (e.g. paraffin) or used as the medium on which the tissue is to be mounted (e.g. Canada balsam).

A

Clearing (de-alcoholization)

Q

Aside from removing alcohol, a clearing agent must also be miscible with [?] and other resins that are used for mounting sections.

A

Canada balsam

Q

remove a substantial amount of fat from the tissue which otherwise presents a barrier to wax infiltration.

A

clearing agent

Q

The most commonly used clearing agent for this purpose is

A

xylene.

Q

are used when the tissue is to be cleared directly from water, as in a frozen section. No de-alcoholization is involved in this process.

A

Glycerin and gum syrup