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MT6321 HISTOPATH > U3 LAB: DEHYDRATION > Flashcards

U3 LAB: DEHYDRATION Flashcards

1
Q

Tissue processing involves?

A
  • dehydration
  • clearing
  • wax infiltration
  • embedding
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2
Q

In Rush Frozen Section, this is done simultaneously.

A
  • fixing
  • embedding
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3
Q

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

A

Paraffin Wax

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4
Q

Paraffin Wax utilizes what as dehydrating fluid?

A

series of alcohol

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5
Q

This is the removal of water from aqueous fixed tissue.

A

Dehydration

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6
Q

What step is introduced since most alcohols and paraffin are not miscible?

A

Clearing

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7
Q

Characteristics of an Ideal Dehydrating Solution

A
  • dehydrate rapidly without producing shrinkage or distortion
  • should not evaporate very fast
  • should be able to dehydrate even fatty tissues
  • should not harden tissues excessively
  • should not remove stains
  • should not be toxic to the body
  • should not be a fire hazard
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8
Q

Characteristics of an Ideal Dehydrating Solution

It should dehydrate rapidly without producing?

A

considerable shrinkage or distortion of tissues

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9
Q

Characteristics of an Ideal Dehydrating Solution

It should be able to dehydrate even?

A

fatty tissues

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10
Q

Characteristics of an Ideal Dehydrating Solution

It should not?

A
  • evaporate very fast
  • harden tissues excessively
  • not be toxic to the body
  • be a fire hazard
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11
Q

Commonly used Dehydrating Agents

A
  • Alcohol
  • Acetone
  • Dioxane
  • Cellosolve
  • Triethyl phosphate
  • Tetrahydrofuran
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12
Q

Dehydrating agents: Alcohol

A
  • Ethanol
  • Methanol
  • Butanol
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13
Q

Recommended for routine dehydration and considered as the best dehydrating agent

A

Ethanol

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14
Q

Ethanol is also known as?

A

Ethyl alcohol

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15
Q

Ethanol

Characteristics

A
  • clear
  • colorless
  • flammable
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16
Q

Ethanol

Advantages

A
  • fast acting
  • mixes with water and many inorganic solvents
  • penetrates tissue easily
  • not poisonous and expensive
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17
Q

Ethanol

Recommended for?

A

routine dehydration

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18
Q

Primarily used for blood and tissue films and for smear preparations.

A

Methanol

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19
Q

Methanol is also known as?

A

Methyl alcohol

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20
Q

Methanol

Disadvantage

A

Toxic to the body

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21
Q

Methanol

If introduced to body, what will be affected first?

A

eyes (blurring of vision)

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22
Q

This is utilized in plant and animal micro-techniques/

A

Butanol

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23
Q

Butanol is also known as?

A

Butyl alcohol

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24
Q

Butanol

Advantages

A
  • slow dehydrating agent
  • less shrinkage and hardening
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25
Q

Butanol

DIsadvantage

A

slow dehydrating agent (not suitable for rapid processing)

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26
Q

Increasing alcohol series

A

60-70% Ethanol > 90-95% Ethanol

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27
Q

99 to 100% Ethanol is also called as?

A

Absolute Alcohol

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28
Q

Points to remember

The strength of initial alcohol required in each concentration will depend on?

A

size, nature, fixative

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29
Q

Smaller and more delicate tissues require ______ concentration and _______ intervals between succeeding ascending grades of alcohol.

A

lower, shorter

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30
Q

These produce shrinkage and make the tissue hard, brittle and difficult to cut.

A

Concentrated alcohols

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31
Q

The tissue may be stored in?

A

70-80% alcohol

(but not for longer periods of time)

32
Q

Prolonged storage in lower concentrations or below _______ tends to _______ the tissue

A

70%, macerate

33
Q

Concentrations ranging from 70-80% alcohol at very long periods of time might interfere with the?

A

staining properties of the specimen

34
Q

Dehydration time will be hastened at?

A

37C for urgent examinations

35
Q

This serves as an indicator that will accelerate removal of water from the dehydrating fluid and insure complete dehydration.

A

Anhydrous Copper Sulfate

36
Q

Anhydrous Copper Sulfate ensures?

A

complete hydration

37
Q

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

A

Acetone

38
Q

Acetone

Advantages

A
  • cheap, rapid-acting dehydrating agent
  • more miscible when epoxy resins than alcohol
39
Q

Acetone

Disadvantages

A
  • highly flammable
  • penetrate tissues poorly
  • causes brittleness (prolonged time)
  • most lipids are removed from tissues
  • extremely volatile and inflammable (small pieces of tissue)
40
Q

Acetone

dehydrates in how many hours?

A

1/2 to 2 hours

41
Q

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

A

Dioxane

42
Q

Dioxane is also known as?

A

Diethylene Dioxide

43
Q

Dioxane

Advantages

A
  • less tissue shrinkage
  • can be left in this reagent for long period of time without affecting consistency or staining properties of the specimen
  • placed directly into solution after washing out
44
Q

Dioxane

Disadvantages

A
  • expensive
  • extremely dangerous
  • ribbon poorly
  • cumulative and highly toxic
45
Q

Dioxane should not be recycled as the risk of _________ increases greatly.

A

creating explosives

46
Q

Time schedule with Dioxane

A

Graupner’s Method

47
Q

Graupner’s method

Pure dioxane solution

A

1st & 2nd: 1 hour
3rd: 2 hours

48
Q

Graupner’s method

Paraffin Wax

A

1st: 15 minutes
2nd: 45 minutes
3rd: 2 minutes

49
Q

This method is when tissues are wrapped in a gauze bag and suspended in a bottle.

A

Weiseberg’s Method

50
Q

Weiseberg’s Method

Bottle contains?

A

Dioxane and little anhydrous calcium oxide

50
Q

Weiseberg’s Method

Water displaced fro tissues is absorbed by?

A

calcium oxide or quicklime

51
Q

Weiseberg’s Method

Dehydration period

A

3-24 hours

52
Q

Tissues which have been treated with a chromate fixative should be?

A

thoroughly washed in running tap water prior to treatment with dioxane

53
Q

Examples of Chromate Fixatives

A
  • Regaud’s
  • Moller’s
54
Q

This is an ethylene glycol monoethyl ether which dehydrates rapidly, and can be stored for months without producing hardening or distortion.

A

Cellosolve

55
Q

Cellosolve

Cautions

A
  • highly flammable (combustible at 110 - 120 F)
  • toxic
56
Q

Cellosolve

If cannot be avoided, what should be used instead of ethylene based glycol ethers?

A

Propylene based glycol ether

57
Q

This removes water very readily and produces very little distortion and hardening.

A

Triethyl Phosphate

58
Q

Triethyl Phosphate

Used to dehydrate?

A

sections and smears

59
Q

Triethyl Phosphate

produce?

A

minimum shrinkage

60
Q

This both dehydrates and clears tissues.

A

Tetrahydrofuran (THF)

61
Q

Tetrahydrofuran

Dissolve many substances including?

A

fats

62
Q

Tetrahydrofuran

Miscible with?

A
  • lower alcohols
  • ether
  • chloroform
  • acetone
  • benzene
63
Q

Tetrahydrofuran

May be used for?

A
  • demixing
  • clearing
  • dehydrating
64
Q

T/F: Tetrahydrofuran gives improved results.

A

True

65
Q

Tetrahydrofuran

Cautions

A
  • toxic
  • should be in well ventilated room
  • avoid if possible
66
Q

This varies per the fixative used in Fixation.

A

Dehydrating schedule

67
Q

This fluid and other alcoholic fluids are directly transferred to 90%, 95% or even absolute alcohol

A

Carnoy’s fluid

68
Q

Carnoy’s fluid is used in?

A

fixing brain for rabies pr Negri bodies

69
Q

These tissues are first dehydrated with 1st stage of 50% alcohol, followed by a graded treatment to prevent tissue shrinkage.

A

Soft tissues

70
Q

Tissues fixed in this fluid is transferred to 90% alcohol.

A

Susa fluid

71
Q

Susa fluid in lower grades of alcohol may cause?

A

swelling of fibrous tissues

72
Q

Typical dehydration sequence for specimens not more than 4mm thick

A

70, 90, 100% Ethanol (x2) - 15 mins
100% Ethanol - 30 mins
100% Ethanol - 45 mins

73
Q

Quality Check for Absolute Alcohol (free of water)

layer of must be employed in dehydrating vessel

A

Anhydrous copper sulfate
- 2-2-5cm thick

74
Q

Quality Check for Absolute Alcohol (free of water)

Anhydrous copper sulfate layer must be covered by?

A

filter paper (prevent contamination)

75
Q

Quality Check for Absolute Alcohol (free of water)

Turns ____ if alcohol gets diluted

A

blue

MT6321 HISTOPATH (15 decks)

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