OTHERY DEHYDRATING AGENTS

1/2 to 2 hours

Acetone is a cheap, rapid-acting dehydrating agent utilized for most urgent biopsies which it dehydrates in

ACETONE

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

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

ACETONE

• Most lipids are removed from tissues with this dehydrating agent

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

ACETONE

• Rapid dehydrating agent

• Less expensive than ethanol

• Does not extract methylene blue and other dyes from stained sections

ACETONE

• May cause less shrinkage of specimen than ethanol

• Not reactive with 0s04 remaining in specimen.

• Miscible with most embedding resins.

ACETONE

• Requires a clearing agent

• Needs good ventilation

• Evaporates rapidly

• Flammable

ACETONE

20

ACETONE- Volume must be ___ times that of the tissue

Uranyl acetate and phosphotungstic acid

ACETONE- are only soluble in dilute solutions of acetone

ACETONE

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

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

DIOXANE

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

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

• Because dioxane is miscible with both water and paraffin, tissues may be placed directly into the solution after washing out

DIOXANE

• tissue sections dehydrated with dioxane tend to ribbon poorly.

• Aside from being expensive, dioxane 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.

Graupner's Method

• (1st) pure dioxane solution 1 hour

• (2nd) pure dioxane solution 1 hour

• (3rd) pure dioxane solution 2 hours

• (1st) Paraffin wax 15 minutes

• (2nd) Paraffin wax 45 minutes

• (3rd) Paraffin wax 2 hours

• Embed in mold and cool in water

Weiseberger's method

the tissue is wrapped in a gauze bag and suspended in a bottle containing dioxane and a little anhydrous calcium oxide. Water is displaced from the tissue by dioxane and in turn absorbed by calcium oxide or quicklime. Dehydration period ranges from 3-24 hours. Tissues which have been treated with a chromate fixative, e.g. Regaud's or Moller's fluid, should be thoroughly washed in running tap water prior to treatment with dioxane in order to remove the chromate.

DIOXANE

• Universal solvent—it dehydrates and clears

• Miscible with water, alcohol, xylene, and paraffin

DIOXANE

• Does not harm tissue over long time periods

• Faster dehydrant than ethanol

DIOXANE

• Needs large volume for dehydration

• Cumulatively toxic

• Odorous

• Distorts tissue-containing cavities

DIOXANE

• Costs about for times more than does absolute alcohol

• Must be used in well-ventilated rooms

• dehydrates rapidly.

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

110-120°F

• Ethylene glycol ethers are combustible at _______

CELLOSOLVE

• 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

CELLOSOLVE

• Rapid dehydrating agent

• Tissue may remain in it for months without injury

CELLOSOLVE

Avoids distortion and does not require graded dilutions

CELLOSOLVE

• Expensive

• Rapidly absorbs water from the air

• Requires clearing agent

TRIETHYLPHOSPHATE

When tissues are fixed, washed and transferred directly into _________ solution for dehydration, it removes water very readily and produces very little distortion and hardening of tissue.

TRIETHYLPHOSPHATE

• May be used in routine paraffin technic

• Displaces water readily with slight distortion

• Does not harden tissue excessively

TRIETHYLPHOSPHATE

• May be used as a dehydrating solution in the staining sequence

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

TETRAHYDOFURAN

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

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

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

TETRAHYDOFURAN

• toxic if ingested or inhaled. V apors cause nausea, dizziness, headache and anesthesia.

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

• Because of this and its rather offensive odor, processing with ____ should be done in a well- ventilated room

TETRAHYDOFURAN

• Rapid without excessive shrinkage and hardening

• Low toxicity; low fire and explosion hazard

• Not toxic

• Better results than most universal solvents

TETRAHYDOFURAN

Solvents of mounting media

TETRAHYDOFURAN

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

TETRAHYDOFURAN

• Odorous- should be used in well-ventilated room

• Evaporates rapidly

• Dyes are not soluble in tetrahydrofuran