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[MT 6321] Histopathology Laboratory > [2S] UNIT 5 Dehydration > Flashcards

[2S] UNIT 5 Dehydration Flashcards

1
Q

T/F: Acetone can be used as a Fixative & dehydrating agent

A

T

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2
Q

Once preserved, the tissue must be processed into a form in which it can be made into thin microscopic sections. This procedure or treatment involves dehydration, clearing, wax infiltration, and embedding.

A

Tissue Processing

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3
Q

TISSUE PROCESSING

Once preserved, the tissue must be processed into a form in which it can be made into thin microscopic sections. This procedure or treatment involves _______, _________, & _________.

A

dehydration, clearing, wax infiltration, and embedding

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4
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 Method

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5
Q

It utilizes series of alcohol as dehydrating fluid.

A

Paraffin Wax Method

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6
Q

is the removal of water from aqueous-fixed tissue

A

Dehyration

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7
Q

T/F: Most alcohols and paraffin are miscible,
another step, known as clearing, is introduced

A

F; not miscible

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8
Q

Since most alcohols and paraffin are NOT miscible,
another step, known as _______, is introduced

A

clearing

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9
Q

CHARACTERISTICS OF AN IDEAL DEHYDRATING SOLUTION

T/F: It should dehydrate rapidly without producing
considerable shrinkage or distortion of tissues.

A

T

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10
Q

CHARACTERISTICS OF AN IDEAL DEHYDRATING SOLUTION

T/F: It should evaporate very fast.

A

F; should not

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11
Q

CHARACTERISTICS OF AN IDEAL DEHYDRATING SOLUTION

T/F: It should not dehydrate fatty tissues.

A

F; It should be able to dehydrate even fatty tissues.

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12
Q

CHARACTERISTICS OF AN IDEAL DEHYDRATING SOLUTION

T/F: It should harden tissues excessively.

A

F; It should not harden tissues excessively.

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13
Q

CHARACTERISTICS OF AN IDEAL DEHYDRATING SOLUTION

T/F: It should not remove stains.

A

T

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14
Q

CHARACTERISTICS OF AN IDEAL DEHYDRATING SOLUTION

T/F: It should not be toxic to the body.

A

T

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15
Q

CHARACTERISTICS OF AN IDEAL DEHYDRATING SOLUTION

T/F: It should not be a fire hazard.

A

T

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16
Q

Most commonly used dehydrating agent

A

Alcohol

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17
Q

Commonly Used Dehydrating Agents

A

A ADCTT (adik)

  1. Alcohol (most common)
  2. Acetone
  3. Dioxane
  4. Cellosolve
  5. Triethyl phosphate
  6. Tetrahydrofuran
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18
Q

It is recommended for routine dehydration of tissues and considered to be the best dehydrating agent.

A

Ethyl Alcohol

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19
Q

Characteristics: Clear, colorless, flammable fluid

A

Ethyl Alcohol

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20
Q

Advantages: Fast-acting, mixes with water and many inorganic solvents, penetrates tissue easily, not poisonous and expensive

A

Ethyl Alcohol

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21
Q

It is primarily used for blood and tissue films, and for smear preparations.

A

Methyl alcohol (methanol)

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22
Q

It is utilized in plant and animal micro-techniques.

A

Butyl alcohol (butanol)

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23
Q

Advantage: Slow dehydrating agent producing less shrinkage and hardening than ethanol.

A

Butyl alcohol (butanol)

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24
Q

Disadvantage: Slow dehydrating agent thus, it is not suitable for rapid tissue processing.

A

Butyl alcohol (butanol)

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25
Q

Using aqueous fixative in tissue processing

A

Fixation

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26
Q

What process?

60-70% Ethanol

A

Dehydration

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27
Q

What process?

2-3 changes of absolute alcohol

A

Clearing

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28
Q

T/F: The strength of initial alcohol required in each concentration will depend upon the size, and nature of the tissue and fixative used.

A

T

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29
Q

T/F: Smaller and more delicate tissues require higher concentration and shorter intervals between succeeding ascending grades of alcohol.

A

F; require lower concentration

30
Q

Produces shrinkage and make the tissue hard, brittle and difficult to cut. Do not penetrate the deeper parts.

A

Concentrated Alcohols

31
Q

What happens if we penetrated the deeper parts of the tissue?

A

Unequal impregnation & poor sectioning

32
Q

Length of storage of tissues in alcohol

A

stored in 70-80% alcohol (not for longer periods of time)

33
Q

T/F: Prolonged storage in lower concentrations (below 70%) tends to macerate the tissue

A

T

34
Q

T/F: Conc. ranging from 70-80% alcohol at very
long periods of time does not interfere with the staining properties of the specimen.

A

F; might interfere

35
Q

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

A

Acetone

36
Q

Advantages
• cheap, rapid-acting dehydrating agent which it dehydrate in ½ to 2 hours
• more miscible when epoxy resins than alcohol

A

Acetone

37
Q

Disadvantages
• highly flammable
• penetrates tissues poorly
• causes brittleness (tissues placed for prolonged period of time)

A

Acetone

38
Q

Disadvantages
• Most lipids are removed from tissues
• extremely volatize and inflammable (limited to small pieces of tissue)

A

Acetone

39
Q

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

A

Dioxane (Diethylene Dioxide)

40
Q

Advantages
• produces less tissue shrinkage
• tissues may be placed directly into the solution after washing out

A

Dioxane (Diethylene Dioxide)

41
Q

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

A

Dioxane (Diethylene Dioxide)

42
Q

Disadvantages
• Expensive
• extremely dangerous
• tissues sections tend to ribbon poorly
• Its vapor produce a cumulative and highly toxic

A

Dioxane (Diethylene Dioxide)

43
Q

T/F: Dioxane is used routinely

A

F; SHOULD NOT BRO

44
Q

T/F: In using dioxane, the laboratory room should be properly ventilated, and all residues should be washed down in the sink.

A

T

45
Q

T/F: Dioxane should not be recycled as the risk of creating explosive peroxides increases greatly

A

T

46
Q

Time schedule for a dehydration with dioxane:

(1st) Pure dioxane solution
(2nd) Pure dioxane solution

A

1 hour

47
Q

Time schedule for a dehydration with dioxane:

(3rd) Pure dioxane solution

A

2 hours

48
Q

Time schedule for a dehydration with dioxane:

(1st) Paraffin wax
(2nd) Paraffin wax
(3rd) Paraffin wax

A
  1. 15 mins
  2. 45 minutes
  3. 2 minutes
49
Q

T/F: Graupner’s Method should be embedded in mold and cool in water

A

T

50
Q

The tissues is wrapped in a gauze bag and suspended in a bottle containing dioxane and a little anhydrous calcium oxide. Water displaced from the tissues by dioxane and in turn absorbed by calcium oxide or quicklime. Dehydration period range from 3-24 hours

A

Weiseberg’s Method

51
Q

Dehydration period range of Weiseberg’s Method

A

3-24 hours

52
Q

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.

A

Dioxane (Diethylene Dioxide)

53
Q

CELLOSOLVE

• Cellosolve dehydrates rapidly
• Stored in it for months without producing hardening or distortion.

A

Ethylene glycol monoethyl ether

54
Q

CELLOSOLVE CAUTION:

• Combustible at ______
• Toxic

A

110-120 F

55
Q

CELLOSOLVE

If cannot be avoided ________ ______ ______ _____ should be used instead of ethylene based glycol ethers

A

propylene based glycol ether

56
Q

Removes water very readily and produces very little
distortion and hardening

A

Triethyl Phosphate

57
Q

• Used to dehydrate sections and smears following
certain stains
• Produce minimum shrinkage

A

Triethyl Phosphate

58
Q

• Both dehydrates and clears tissues
• Dissolve many substances including fats

A

Tetrahydrofuran (THF)

59
Q

• Miscible with lower alcohols, ether, chloroforms, acetone, benzene
• May be used for demixing, clearing and dehydrating paraffin section

A

Tetrahydrofuran (THF)

60
Q

Most staining procedures give improved results with _________

A

Tetrahydrofuran (THF)

61
Q

T/F: THF is toxic, should be in a well-ventilated room & avoided if possible.

A

T

62
Q

Many of these dehydrating agents are alcohols of various types that are generally used in increasing strengths to remove aqueous tissue fluids with
little disruption to the tissue caused by ________ ______.

A

diffusion currents

63
Q

ODD ONE OUT: REAGENT TIME

70% Alcohol
Alcohol-I
Xylol-I
10% Formalin

A

10% Formalin kc sha lng 1 hr

Paraffin-I & II - 2 hrs d rest 1:30 h

64
Q

T/F: The dehydrating schedule varies as per the
fixative used in the process of Fixation.

A

T

65
Q

In case of Carnoy’s fluid and other alcoholic fixatives, the tissues are directly transferred to?

A

90% or 95% or even Absolute alcohol

66
Q

What alcohol is used for soft tissues like an embryo and is followed by a graded treatment of the alcohol to prevent tissue shrinkage?

A

50% Alcohol

67
Q

Tissues fixed in ____ ______ are transferred to 90%
alcohol because lower grades of alcohol may
cause swelling of the fibrous tissues.

A

Susa fluid

68
Q

Dehydration sequence for specimens not more
than 4mm thick

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

69
Q

QUALITY CHECK FOR ABSOLUTE ALCOHOL

To ensure that the final bath of the alcohol containing the absolute alcohol or ethanol is free of water, a layer of _______ _____ ________ which should be approx. 2-2-5 cm thick, covered by filter paper to prevent the contamination, is employed in dehydrating vessel.

A

Anhydrous copper sulfate

70
Q

QUALITY CHECK FOR ABSOLUTE ALCOHOL

Color of alcohol if it gets diluted

A

Blue

71
Q

QUALITY CHECK FOR ABSOLUTE ALCOHOL

Color of alcohol if it gets diluted

A

Blue

[MT 6321] Histopathology Laboratory (7 decks)

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