Histopath Lab - Dehydration

Dehydration

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

alcohols

Many of these dehydrating agents are (?) of various types that are generally used in increasing strengths to remove aqueous tissue fluids with little disruption to the tissue

30%

For delicate tissues- starting with (?) ethanol is recommended

10 times

GENERAL RULE: Whatever dehydrating agent is used, the amount in each stage should not be less than (?) the volume of the tissue in order to ensure complete penetration of the tissue by dehydrating solution

Alcohol

Most common dehydrating agent

Ethanol

Alcohol recommended for routine dehydration of tissues

Ethanol

Considered to be the best dehydrating agent

Methanol

Most toxic dehydrating agent

Methanol

Dehydrating agent primarily employed for blood and tissue films and for smear preparations

Butanol

Recommended for tissues which do not require rapid processing

Acetone

Cheap, rapid-acting dehydrating agent utilized for most urgent biopsies

1/2 - 2 hours

Acetone dehydration time

True

True or False:

Acetone is not recommended for routine dehydration purposes

Acetone

Limited use only to small pieces of tissues due to extremely volatility and inflammability

Dioxane

An excellent dehydrating and clearing agent readily miscible in water, melted paraffin, alcohol and xylol- tissues may be placed directly into the solution after washing out

Dioxane

Expensive and extremely dangerous- its vapor produces a cumulative and highly toxic action in man

Graupner's method

A combination of pure dioxane solution and paraffin wax embed in mold and cooled 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

anhydrous calcium oxide

Weiseberger's method

The tissue is wrapped in a gauze bag and suspended in a bottle containing dioxane and a little (?)

3-24 hours

Dehydration period of Weiseberger's method

Ethelyne glycol monoethyl ether

AKA Cellosolve

True

True or False:

Tissues may be transferred from water or normal saline directly to cellosolve and stored for months without hardening or distortion

110-120

Cellosolve is combustible at (?)°F and toxic by inhalation, skin contact, and ingestion

Propylene-based glycol ethers

If the use of cellosolve cannot be avoided, what should be used?

Tetrahydrofuran (THF)

A reagent that both dehydrates and clears tissues- miscible in both water and paraffin

Tetrahydrofuran

Can dissolve many substances- fats

aniline dyes

Tetrahydrofuran does not dissolve (?)

Cellosolve

Has a flash point of 110-120 F

Tetrahydrofuran

An eye and skin irritant and prolonged exposure may cause conjunctival irritation

Tetrahydrofuran

Vapor causes nausea, dizziness, headache and anesthesia