dehydration

Question 1

preeminent type of tissue processing treatment considered to be the most suitable for routine preparation, sectioning, staining, and subsequent storage of large tissue samples.

Answer 1

Paraffin Wax Method

Question 2

process that removes water from aqueous-fixed tissue to prepare it for further processing

Answer 2

Dehydration

Question 3

step that makes tissue miscible with paraffin wax

Answer 3

Clearing

Question 4

most common dehydrating agent used in tissue processing

Answer 4

Alcohol

Question 5

ideal characteristics of a dehydrating solution

Answer 5

1. Dehydrates rapidly without causing shrinkage or distortion.
2. Does not evaporate too fast.
3. Can dehydrate fatty tissues.
4. Does not excessively harden tissues.
5. Does not remove stains.
6. non-toxic.
7. not a fire hazard.

Question 6

commonly used dehydrating agents aside from alcohol

Answer 6

Acetone, Dioxane, Cellosolve, Triethyl phosphate, Tetrahydrofuran

Question 7

T/F Alcohol and paraffin wax are naturally miscible, so no additional step is needed after dehydration.

Answer 7

F (Clearing is required because alcohol & paraffin are not miscible)

Question 8

T/F Common dehydrating agents like alcohol are preferred because they are non-toxic and not hazardous.

Answer 8

T

Question 9

T/F Paraffin wax is used in tissue processing because it is unsuitable for large tissue samples.

Answer 9

F - considered most suitable for routine processing and large tissue samples

Question 10

dehydrating fluid in paraffin wax method

Answer 10

alcohol

Question 11

best dehydrating agent recommended for routine tissue dehydration

Answer 11

Ethyl alcohol (ethanol)

Question 12

characteristics of ethyl alcohol used as a dehydrating agent

Answer 12

clear, colorless, and flammable

Question 13

Odd One Out: Advantage of ethyl alcohol as a dehydrating agent

A) Fast-acting
B) Non-toxic
C) Expensive
D) Mixes with water and solvents

Answer 13

Expensive – Ethanol is not expensive.

Question 14

alcohol primarily used for blood and tissue films and smear preparations but is toxic

Answer 14

Methyl alcohol (methanol)

Question 15

T/F Butyl alcohol is a slow dehydrating agent used in both plant and animal micro-techniques.

Answer 15

True

Question 16

Slow dehydrating agent producing less shrinkage and hardening than ethanol.

Answer 16

Butyl alcohol (butanol)

Question 17

disadvantage of using butyl alcohol as a dehydrating agent

Answer 17

slow dehydrating agent -> unsuitable for rapid tissue processing.

Question 18

In Paraffin Wax Method, what concentration of ethanol is used after initial dehydration with 60-70% ethanol?

Answer 18

90-95% ethanol

Question 19

T/F For smaller, more delicate tissues, lower alcohol concentrations are required for dehydration.

Answer 19

T

Question 20

T/F Unequal impregnation and poor sectioning happens when concentrated alcohols produce shrinkage and make the tissue hard, brittle and difficult to cut – making it unable to penetrate the deeper parts.

Answer 20

T

Question 21

what happens to tissue stored for extended periods in alcohol concentrations below 70%?

Answer 21

macerates and becomes unsuitable for processing.

Question 22

dehydration time will be hastened at __ C for urgent examinations

Answer 22

37°C

Question 23

chemical added to the dehydrating fluid to remove water and ensure complete dehydration

Answer 23

Anhydrous Copper Sulfate

Question 24

clear, colorless fluid that mixes with water, ethanol and most organic solvent

Answer 24

Acetone

Question 25

Odd One Out: Acetone as a dehydrating agent A) Cheap B) Rapid-acting C) Penetrates tissue well D) Miscible with organic solvents

Answer 25

C) Penetrates tissue well – Acetone penetrates tissues poorly.

Question 26

T/F Acetone is highly flammable and should be used with caution.

Answer 26

T

Question 27

dehydrating agent that is an excellent clearing agent, produces less tissue shrinkage, but is toxic and expensive?

Answer 27

Dioxane (Diethylene Dioxide)

Question 28

T/F Dioxane can be used routinely in tissue processing.

Answer 28

F - Dioxane is dangerous and should not be used routinely.

Question 29

Time Schedule for dehydration with dioxane (Graupner's Method) (1st) Pure dioxane solution: __ (2nd) Pure dioxane solution: __ (3rd) Pure dioxane solution: __ (1st) Paraffin wax: __ (2nd) Paraffin wax: __ (3rd) Paraffin wax: __ Embed in mold and cool in water

Answer 29

1 hr - 1 hr - 2 hr - 15 min - 45 min - 2 min

Question 30

dehydration method that uses dioxane and anhydrous calcium oxide to remove water from tissues

Answer 30

Weiseberg’s Method

Question 31

Tissues treated with ______ fixatives must be washed thoroughly before being placed in dioxane.

Answer 31

chromate

Question 32

Odd One Out: Advantage of dioxane A) Produces less tissue shrinkage B) Allows tissue to stay in solution for a long time C) Cheap D) Can be left without affecting staining properties

Answer 32

C) Cheap – Dioxane is expensive.

Question 33

dehydrating agent that can store tissues for months without causing hardening or distortion?

Answer 33

Cellosolve

Question 34

cellosolve utilizes what chemical

Answer 34

ethylene glycol monoethyl ether

Question 35

T/F: Cellosolve is combustible and toxic, and should be handled with caution

Answer 35

T

Question 36

safer alternative if ethylene-based glycol ethers like Cellosolve cannot be avoided

Answer 36

propylene-based glycol ethers

Question 37

dehydrating agent that removes water readily and produces minimal distortion and shrinkage

Answer 37

Triethyl phosphate

Question 38

agent in tissue processing that dehydrates sections and smears following certain stains.

Answer 38

triethyl phosphate

Question 39

Odd One Out: Characteristic of triethyl phosphate A) Removes water readily B) Produces minimal shrinkage C) Excessively hardens tissue D) Dehydrates without distortion

Answer 39

C) Excessively hardens tissue – Triethyl phosphate does not excessively harden tissue.

Question 39

dehydrating agent that also acts as a clearing agent, dissolves many substances including fats, and gives improved staining results

Answer 39

Tetrahydrofuran (THF)

Question 39

Odd One Out: NOT an advantage of Tetrahydrofuran (THF)? A) Dehydrates and clears tissues B) Dissolves many substances, including fats C) Non-toxic D) Improves staining results

Answer 39

Non-toxic – THF is toxic.

Question 40

T/F Tetrahydrofuran (THF) can be used in poorly ventilated rooms as long as it is handled with care.

Answer 40

False – only used in well-ventilated rooms due to toxicity.

Question 40

fixative that requires tissue to be transferred directly to 90% or higher ethanol for dehydration

Answer 40

Carnoy’s fluid and other alcoholic fixatives

Question 40

For soft tissues like embryos, what is the first concentration of alcohol used to prevent shrinkage?

Answer 40

50% alcohol, followed by graded alcohol treatments.

Question 41

T/F Tissues fixed in Susa fluid are transferred to 90% alcohol to avoid swelling of fibrous tissues.

Answer 41

T

Question 42

typical dehydration sequence for specimens not more than 4 mm thick

Answer 42

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

Question 43

chemical used to check the quality of absolute alcohol by detecting water contamination?

Answer 43

Anhydrous copper sulfate

Question 44

What color does anhydrous copper sulfate turn if the absolute alcohol is contaminated with water?

Answer 44

blue

Question 45

T/F Dehydration can be performed automatically in tissue processors (HP).

Answer 45

T

Question 46

T/F Prolonged storage of tissues in alcohol concentrations below 70% tends to macerate the tissue.

Answer 46

T

Question 46

T/F Tissues fixed in Susa fluid are transferred to 9% alcohol because lower grades of alcohol may cause swelling of the fibrous tissues

Answer 46

False – 90% alcohol.

Question 47

Odd One Out: Factors to consider in choosing strength of initial alcohol a) size b) weight c) nature of the tissue d) fixative used.

Answer 47

b) Weight

Question 48

conc. ranging from 70-80% alcohol at very long periods of time might interfere with the _____ properties of the specimen.

Answer 48

staining

Question 49

acetone is more miscible when _____ than alcohol

Answer 49

epoxy resins