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HSTCYT1 > CLEARING/IMPREGNATION/EMBEDDING > Flashcards

CLEARING/IMPREGNATION/EMBEDDING Flashcards

1
Q

Removal of dehydrating agent from the tissues and replacing it by a solvent

A

Clearing

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2
Q

Removal of dehydrating agent from the tissues and replacing it by a solvent

A

Clearing

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3
Q

Produce transparent and translucent tissue

A

Clearing

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4
Q

True or false
- not all dealcoholizing agents act as clearing agent

A

True

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5
Q

When is clearing in embedding done

A

Done after dehydration and before infiltration

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6
Q

Agents for clearing in embedding

A
  • xylene
  • toluene
  • Dioxane
  • chloroform
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7
Q

When is clearing in mounting done

A

Done after staining and before mounting

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8
Q

Agents of mounting media

A
  • xylene
  • toluene
  • terpineol
  • carbol - xylene
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9
Q

An ideal clearing agent should be miscible with

A

Alcohol and paraffin wax

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10
Q

Most commonly and rapidly used clearing agent

A

Xylene/ xylol

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11
Q

Duration of xylene

A

15-30 mins or 30 mins - 1 hr

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12
Q

Excellent clearing agent but tends to make tissues excessively hard and brittle

A

Xylene/xylol

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13
Q

Can be used for celloidin sections

A

Xylene

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14
Q

Unsuitable for brain and lymph nodes

A

Xylene

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15
Q

Turns milky when dehydration is not complete

A

Xylene

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16
Q

Rapid agent and highly inflammable; doesn’t make tissues hard and brittle but may cause considerable shrinkage

A

Benzene

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17
Q

Excessive exposure to this may be extremely toxic to man and may become carcinogenic or it may damage the bone marrow resulting in aplastic anemia

A

Benzene

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18
Q

Duration of benzene

A

15-60 mins

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19
Q

Similar to xylene but does not harden tissues nearly so much

A

Toluene/toloul

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20
Q

Slower than xylene or benzene, it is not carcinogenic but emits toxic fumes

A

Toluene

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21
Q

Duration of toulene or toluol

A

1-2 hours

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22
Q

For nervous tissues, lymph nodes, and embryos

A

Chloroform

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23
Q

Best for large specimens and tough tissues

A

Chloroform

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24
Q

Little shrinkage and doss not harden tissues excessively; not flammable

A

Chloroform

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25
Q

Slow and doesn’t make tissues transparent, it is toxic to the liver on prolonged inhalation

A

Chloroform

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26
Q

Tissues tend to float in chloroform, how to avoid this

A

Wrap the tissues with absorbent cotton gauze to facilitate sinking of the section in solution

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27
Q

Recommended for CNS, smooth muscles, and skin

A

Cedarwood oil

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28
Q

Used to clear both paraffin and celloidin sections during the embedding process

A

Cedarwood oil

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29
Q

Duration of clearing using Cedarwood oil

A

2-3 days

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30
Q

Slow clearing (2-3 days) with minimal shrinkage

A

Cedarwood oil

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31
Q

Must be followed by immersion in xylene or benzene to remove oil from tissues, and must be filtered prior to using

A

Cedarwood oil

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32
Q

Turns milky on prolonged storage

A

Cedarwood oil

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33
Q

Tissue floats in cedarwood oil, what is the remedy

A

Superimpose with absolute alcohol

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34
Q

This is not normally utilized as a routine agent but it is recommended for clearing embryos, insects, and very delicate specimens, due to its ability to clear 70% alcohol without excessive tissue shrinkage and hardening

A

Aniline oil

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35
Q

It has the ability to clear 70% alcohol without excessive tissue shrinkage and hardening

A

Aniline oil

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36
Q

Slow, may be adultered, removes aniline dyes

A

Clove oil

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37
Q

Aniline dyes are removed, and celloidin is dissolved

A

Clove oil

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38
Q

Similar to chloroform

A

CCL4

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39
Q

Fill all natural cavities, spaces and interstices of the tissue with a firm consistency

A

Impregnation or infiltration

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40
Q

Impregnated tissues are placed into a precisely arranged position in a mold containing a medium which is the allowed to solidify

A

Embedding, blocking, or casting

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41
Q

Simplest, most common and best embedding medium used for routine tissue processing

A

Paraffin wax

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42
Q

Shrinks about 10% on cooling

A

Paraffin wax

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43
Q

Melting point for normal routine work

A

56C

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44
Q

At what temp should the paraffin oven adjusted

A

2-5C higher

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45
Q

Temperature adjustment if the lab temp is 20-24C

A

54-58C

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46
Q

Temperature adjustment if lab temp is 15-18C

A

50-54C

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47
Q

Not recommended for fatty tissues

A

Paraffin wax

48
Q

T/f: paraffin wax allows storage for an indefinite period

49
Q

Paraffin wax disadvantages

A

*Overheating = brittle tissue
* Prolongation= excessive shrinkage and hardening
* Inadequate infiltration= soft and shrunken

50
Q

At least 4 changes of wax are required at 15 mins interval in order to ensure complete removal of clearing agent from the tissue

A

Manual processing

51
Q

2-3 changes of wax are required to remove the clearing agent and properly impregnate the specimen with constant agitation

A

Automatic processing

52
Q

Temp of wax bath for automatic processing

A

At least 3C greater than MP

53
Q

MP

A

Melting point

54
Q

Negative atmospheric pressure

A

Vacuum embedding

55
Q

Negative atmospheric pressure of vacuum embedding

A

400-500 mmHg

56
Q

Embedding that is Recommended for urgent biopsies and delicate tissues

A

Vacuum embedding

57
Q

Temp of vacuum embedding above mp of wax

58
Q

Advantage: effects of heat are prevented

A

Vacuum embedding

59
Q

Substitute for paraffin wax

A
  1. Paraplast
  2. Embeddol
  3. Ester wax
  4. Water soluble waxes ( 38-41 or 46-56)
60
Q

Melting point of paraplast

61
Q

Highly purified paraffin and synthetic plastic polymers with a melting point of 56-57C

62
Q

Hastens the removal of air bubbles and clearing agent from the tissue block

A

Vacuum embedding

63
Q

Urgent biopsies, for delicate tissues such as lung, brain, connective tissues, decalcified bones, eyes, spleen, cns

A

Vacuum embedding

64
Q

With vacuum embedding, the time required for complete impregnation is reduced by ___ of the normal time required for tissue processing

65
Q

More elastic and resilient and doesn’t crumble

66
Q

Better ribboning with ease and doesn’t require cooling

67
Q

Better ribboning with ease and doesn’t require cooling

68
Q

At what temp should the paraffin oven must be maintained to be used for impregnated

A

2-5C above melting point

69
Q

Water must therefore be removed by heating the wax to ____ thereby raising its melting point

70
Q

Mp of embeddol

71
Q

Synthetic wax substitutes similar to paraplast

72
Q

Less brittle and less compressible than paraplast

73
Q

Two types of embeddol

A
  • bioloid
  • tissue mat
74
Q

Semisynthetic wax recommended for embedding eyes

75
Q

Product of paraffin, containing rubber, with the same property as paraplast

A

Tissue mat

76
Q

Has a lower mp, but it is harder than paraffin

77
Q

Mp of ester wax

78
Q

It is not soluble in water, but is soluble in 95% ethyl alcohol and can be used for impregnation without prior clearing of the tissue

79
Q

Examples of heavy duty microtome

A

Sliding or sledge type

80
Q

How many changes of ester wax are required to ensure complete tissue impregnation

A

3-4 changes

81
Q

Plastic polymers, mostly polyethylene glycols

A

Water soluble waxes

82
Q

Mp of water soluble waxes

A
  • 38-41C
  • 46-56C
83
Q

Most commonly used water soluble waxes

84
Q

Polyethylene glycol containing 18 or more carbon atoms, which appears solid at RT

85
Q
  • Does not require dehydration and clearing
  • does not remove neutral fats and lipids
  • suitable for enzyme srudies
86
Q

Carbowax processing

A

*70% - 90% - 100% (2x) at 56C
* Blocking at 50C

87
Q

What should be added to water to reduce tissue distortion and promote flattening and floating out of sections

A
  • add soap to water or using 10% polyethylene glycol 900
88
Q

Highly soluble in water and hygroscopic; cannot be floated in water

89
Q

Purified form of nitrocellulose soluble in many solvents, suitable for specimens with large hollow cavities which tend to collapse

A

Celloidin or collodion

90
Q

Two methods for celloidin impregnation for tissue

A
  • wet celloidin method
  • dry celloidin method
91
Q

For bones, teeth, large brain scetions and whole organs

A

Wet method

92
Q

Evaporating solvent ( until no fingerprint may be observed)

A

Wet method

93
Q

In what solvent should method be stored and used as a lubricant

A

70-80% alcohol

94
Q

Celloidin embedding that is for the whole eye sectioning

A

Dry method

95
Q

In what reagent should the dry method be stored

A

Gilson’s mixture

96
Q

Components of gilson’s mixture

A

Chloroform and cedarwood oil

97
Q

Types of plastic/resin embedding medium

A
  1. Epoxy
  2. Polyster
  3. Acrylic
98
Q

Types of epoxy

A

-Araldite base (bisphenol)
-glycerol (epon)
- cyclohexane dioxide (spurr)

99
Q

Slowest type of epoxy

A

Araldite base (bisphenol)

100
Q

Fastest type of epoxy

A

Cyclohexene dioxide (spurr)

101
Q

Toxic component of epoxy that is carcinogenic

A

VCD (vinyl cyclohexane dioxide)

102
Q

Plastic embedding medium for EM

103
Q

Plastic embedding medium for high resolution LM

104
Q

2 applications of acrylic

A

*GMA - Glycol methacrylate
*MMA - Methyl methacrylate

105
Q

Application of acrylic that is hydrophilic and allows wide stain selection

A

Glycol methacrylate

106
Q

Application of acrylic that is for hardness, for dense tissues

A

Methyl methacrylate

107
Q

Rarely used except when dehydration is to be avoided and when tissues are to be subjected to histochemical and enzyme studies

A

Gelatin impregnation

108
Q

For delicate specimens, histochemical and enzyme studies, and for frozen sections

A

Gelatin embedding

109
Q

Why is gelatyaccompanied with phenol?

10% gelatin - 10% - 20% - (+1% phenol)

A

Gelatin embedding

110
Q

How many times should paraffin wax be used

111
Q

At what temp is water removed by heating paraffin

112
Q

At what temp are tissues submerged in two or more changes of melted paraffin wax in the paraffin oven or incubator

113
Q

When the tissue is to be cleared directly from water (no dealcoholization, it merely improves the RI)

A

Glycerin, Gum syrup and Brun’s sltn

114
Q

Slow, used in double embedding

A

Methyl benzoate

115
Q

Dehydrating and clearing agent

116
Q

For large pieces of tissues and embryonic materials

A

Amyl acetate

HSTCYT1 (18 decks)

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