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Hpct > LEC 10 - CLEARING > Flashcards

LEC 10 - CLEARING Flashcards

1
Q

Transition step between dehydration and infiltration with the
embedding medium

A

CLEARING

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2
Q

Process whereby alcohol is removed from the tissue and
replaced with a substance that will dissolve the wax with
which the tissue is impregnated (paraffin) or the medium on
which the tissue is to be mounted (Canada Balsam)

A

clearing

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3
Q

Most commonly used clearing agents are

A

xylene, dioxane, chloroform and cedarwood oil

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4
Q

The clearing agent will make microscopic tissue
preparations __due to their high index refraction

A

transparent

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5
Q

__ is often used as an
indication of the effectiveness or completeness of the
clearing process

A

Optical clarity or transparency

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6
Q

purpose of clearing

A

transition between dehydration and infiltration
make the tissue transparent
remove a substantial amount of fat from the tissue

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7
Q

Characteristics of a Good Clearing Agent

A

miscible with alcohol to promote rapid removal for the dehydrating agent

should be miscible with and easily removed by melted paraffin wax

should not produce excessive shrinkage, hardening or damage of tissue

should not dissolve out aniline dyes

should not evaporate quickly in a water bath

should make tissues transparent

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8
Q

choice of clearing agent depends upon

A

the type of tissues to be process, and the type of processing to be undertaken

the processor system to be used

intended processing conditions such as temperature, vaccum, and pressure

safety factors

cost and convenience

speedy removal of dehydrating agent

ease of removal by molten paraffin wax

minimal tissue damage

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9
Q

factors affecting clearing agent

A

clearing fluids with a low boiling point are generally more readily replaced by melted paraffin, although chloroform which has a lower boiling point than xylene in fact takes longer than the latter to clear

viscosity also affects the speed of penetration of clearing agent

prolonged exposure to most clearing agents causes the tissues to become brittle and therefore more difficult to cut

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10
Q

xylene is also called as

A

xylol

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11
Q

clearing time of xylene

A

30 mns to 1hr

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12
Q

used for clearing, both for embedding and mounting procedures

A

xylene (xylol )

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13
Q

also used in cover slipping, in cleaning tissue processors as solvent to remove synthetic immersion oil from the microscope objective in recycling of used slides

A

xylene (xylol )

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14
Q

most rapid clearing agent, suitable for urgent biopsies

A

xylene

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15
Q

xylene is applicable to tissues with maximum __ thichness

A

5 mm

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16
Q

can xylene extract aniline dye?

A

no

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17
Q

can xylene be used in celloidin section?

A

yes, it does nit dissolve celloidin

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18
Q

this evaporates quickly in paraffin oven and can, therefore, be readily replaced by wax during impregnation and embedding

A

xylene

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19
Q

is xylene expensive?

A

nope

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20
Q

xylene

highly flammable and should be appropriately stored

A

true

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21
Q

if xylene is used for more than 3 hrs, it will make the tissues __

A

excessively hard and brittle

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22
Q

what type of tissue is xylene not applicable for as it can cause hardening and shrinkage to them

A

nervous tissue and lymph nodes

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23
Q

xylene can iritate

A

eyes, nose, respiratory tract

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23
Q

xylene will become milky if an incomplete __ is immersed in it

A

dehydration

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24
Q

xylene can be absorbed through the skin and cause
___

A

dermatitis

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25
Q

at high concentration, it is toxic and narcotic

A

xylene

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26
Q

keep container tightly closed to prevent xylene from

A

subliming and entering the atmosphere

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27
Q

only __ tools may be used to handle xylene

A

non sparking

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28
Q

it is highly recommended that all chemical be stored BELOW eye level so cracking or leaking of containers are immediately visible and there is less potential chemicals falling unto lab workers when pulling from shelves

t or f

A

true

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29
Q

transport chemicals in closed containers, in the BIGGEST amount possible, and use aids such as carts, chemical transport carriers, etc.

A

false, must be smallest amount possible

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30
Q

clearing time of toluene

A

1-2 hrs

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31
Q

better at preserving tissue structure and is more tolerant of small amounts of water left behind in the tissues than xylene

A

toluene

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32
Q

toluene is can be used as substitute for __

A

xylene and benzene

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33
Q

toluene is miscible with both

A

absolute alcohol and paraffin

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34
Q

acts fairly rapidly and is recommended for routine purposes

A

toluene

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35
Q

tissues do not become excessively hard and brittle even in left for 24 hrs

A

toluene

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36
Q

clears overnight and is not carcinogenic

A

toluene

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37
Q

relatively slower than xylene and benzene

A

toluene

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38
Q

tends to acidify in a partially filled vessel

A

toluene

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39
Q

highly concentrated solutions of toluene will emit __that are toxic upon prolonged exposure

A

fumes

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40
Q

which one is more expensive

toluene or xylene

A

toluene

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41
Q

clearing time of benzene

A

15-60 mns

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42
Q

preferred as clearing agent in the embedding process of tissues because it penetrates and clears tissues rapidly

A

benzene

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43
Q

rapid acting, recommended for urgent biopsies (15-60 mns ) and routine purposes

A

benzene

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44
Q

volatilizes rapidly in paraffin oven and is therefore easily eliminated from the tissues

A

benzene

45
Q

this clearing agent does not make tissues hard and brittle but it causes minimum shrinkage

A

benzenei

46
Q

makes tissues transparent and clears overnight

A

benzene

47
Q

is benzene flammable?

A

yes

48
Q

if section is left in benzene for a long time, what will happen?

A

considerable tissue shrinkage may be observed

49
Q

excessive exposure to benzene is __ and __ to human

A

toxic and carcinogenic

50
Q

benzene can damage the bone marrow resulting in __

A

aplastic anemia

51
Q

chloroform clearing time is

A

6-24 hrs

52
Q

this clearing agent is suitable for large tissue specimens

A

chloroform

53
Q

chloroform can clear tissue blocks up to ____ cm

A

1 cm

54
Q

recommended for routine work (6-24 hrs )

A

chloroform

55
Q

recommended for tough tissues, nervous tissues, lymph nodes and embryos

A

chloroform

56
Q

why do chloroform is recommended for tough tissues, nervous tissues, and lymph nodes and embryos?

A

it causes minimum shrinkage and hardening or the tissues

57
Q

relatively toxic to the ___ after prolonged inhalation of chloroform

A

liver

58
Q

wax impregnation after chloroform clearing is relatively __

fast or slow

A

slow

59
Q

this clearing agent does not make tissues transparent

A

chloroform

60
Q

this clearing agent is not very volatile in paraffin oven

A

chloroform

61
Q

difficult to remove from paraffin sections because it is not very volatile

A

chloroform

62
Q

may produce considerable deterioration of the wax

A

chloroform

63
Q

its vapor may attack the rubber seal used in vacuum impregnating bath

A

chloroform

64
Q

this clearing agent’s complete clearing is difficult to evaluate

A

chloroform

65
Q

tissues tend to float in this clearing agent

A

chloroform

66
Q

tissue floating in chloroform is avoided by ___

A

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

67
Q

clearing time of cedarwood oil

A

2-3 days

68
Q

used to clear both paraffin and celloidin sections during embedding process

A

cedarwood oil

69
Q

recommended for central nervous system tissues and cytological studies

A

cedarwood oilve

70
Q

cedarwood oil is miscible wth ___ alcohol which it removed readily

A

96%

71
Q

how many days can cedarwood oil clear celloidin

A

5-6 days

72
Q

tissues can be left in cedar wood oil indefinitely without considerable damage and distortion

true or false

A

true

73
Q

is cedarwood oil can be dissolve in aniline dyes

A

nope

74
Q

this does not harden the tissues and does not interfere too seriously with paraffin penetration if it is not completely removed

A

cedarwood oil

75
Q

can cedarwood oil make tissues transparent?

A

yes

76
Q

this clearing agent often improves cutting of the section

A

cedarwood oil

77
Q

due to its slow capability as a clearing agent, it is not recommended for routine purposes

A

cedar wood oil

78
Q

becomes milky upon prolonged storage and should be filtered before use

A

cedar wood oil

79
Q

hard to eliminate from the tissues in paraffin bath, making the wax impregnation very slow

A

cedarwood oil

80
Q

since cedarwood oil is hard to be replaced by the impregnation wax, we can hasten it by

A

transferring the specimen from oil to benzene for 30 mns before finally placing the tissue in wax

81
Q

this clearing agent’s quality is not always uniform and good

A

cedarwood oil

82
Q

in this clearing agent, tissues initially float before gradually staying to bottom as clearing proceeds

A

cedarwood oil

83
Q

this clearing agent may fry out the tissue before it is completeley cleared

A

cedarwood oil

84
Q

how to prevent the frying out of tissue caused by cedar wood oil

A

this can be prevented by superimposing absolute alcohol on the surface of the clearing agent. Once saturated, the specimen should then be transferred to a fresh solution of cedarwood oil

85
Q

a cedarwood oil that has been previously used to clear acetic-alcohol fixed tissues may produce what

A

crystals with a melting point of approximately 35*C and therefore interfere with adequate clearing of tissue

86
Q

remedy in the crystals formed because of cedarwood oil used in acetic-alcohol fixed tissues

A

the solution must be heated to 200*C in order to dissolve crystals and restore the solution to its normal state

87
Q

do tissues become translucent if cleared with cedar wood oil

A

no

88
Q

is cedarwood oil as clearing agent expensive?

A

very expensive

89
Q

is aniline oil used as a routine clearing agent

A

no

90
Q

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

91
Q

the only advantage of clove oil

A

causes minimum shrinkage of tissues

92
Q

clove oil

its quality is not guaranteed due to its tendency to become __

A

adulterated

93
Q

wax impregnation after clearing with oil is

A

slow and difficult

94
Q

effect of clove oil to tissues, aniline dyes, and celloidin

A

tissues become brittle
aniline dyes are removed
celloidin is dissolved

95
Q

unsuitable for routine clearing purposes

A

clove oil

96
Q

its properties are similar to chloroform

A

carbon tetrachloride

97
Q

it produces considerable tissue hardening and dangerous to inhale on prolonged exposure due to its highly toxic effects

A

carbon tetrachloride

98
Q

relatively toxic to liver as well after prolonged inhalation aside from chloroform

A

carbon tetrachloride

99
Q

can carbon tetrachloride make tissues transparent?

A

nope

100
Q

CARBON TETRACHLORIDE

easy to remove from paraffin sections because it is very volatile

A

false

101
Q

ability to perform two processes at the same time, thereby shortening the total processing time and allowing more time for fixation

A

tetrahydrofuran

102
Q

non toxic but has offensive odor and should be used in a well-ventilated room

A

tetrahydrofuran

103
Q

slow acting clearing agents that can be used when double embedding techniques aree required

A

methyl benzoate and methyl salicylate

104
Q

clearing agent for frozen section and no de alcoholization is involved in the process

A

glycerin and gum syrup

105
Q

dehydration time if 10% formol saline is used

running water -
alcohol 30 % -
alcohol 50 % -
alcohol 70 % -
alcohol 90 % -
absolute alcohol 1
abs alcohol 2
abs alcohol 3

A

dehydration time if 10% formol saline is used

running water -
alcohol 30 % -
alcohol 50 % -
alcohol 70 % - 3-12 hr
alcohol 90 % - 1-2 hr
absolute alcohol 1 - 1-2 hr
abs alcohol 2 - 1 - 2 hr
abs alcohol 3 - 1-2 hr `

106
Q

dehydration time if zenker’s or helly’s fluid is used

running water -
alcohol 30 % -
alcohol 50 % -
alcohol 70 % -
alcohol 90 % -
absolute alcohol 1
abs alcohol 2
abs alcohol 3

A

running water - 1-12 hrs
alcohol 30 % - 1-6 hrs
alcohol 50 % - 1-6 hrs
alcohol 70 % - 1-6 hrs
alcohol 90 % - 1-6 hrs
absolute alcohol 1 - 1-2 hrs
abs alcohol 2 - 1-2 hrs
abs alcohol 3 - 1-2 hrs

107
Q

dehydration time if bouin’s fluid is used

running water -
alcohol 30 % -
alcohol 50 % -
alcohol 70 % -
alcohol 90 % -
absolute alcohol 1
abs alcohol 2
abs alcohol 3

A

running water -
alcohol 30 % -
alcohol 50 % -
alcohol 70 % - 3-12 hrs
alcohol 90 % - 3-12 hrs
absolute alcohol 1 - 1-2 hrs
abs alcohol 2 - 1-2 hrs
abs alcohol 3 - 1-2 hrs

108
Q

dehydration time if susa, carnoy or formol sublimate is used

running water -
alcohol 30 % -
alcohol 50 % -
alcohol 70 % -
alcohol 90 % -
absolute alcohol 1
abs alcohol 2
abs alcohol 3

A

running water -
alcohol 30 % -
alcohol 50 % -
alcohol 70 % -
alcohol 90 % - 1-6 hrs
absolute alcohol 1 - 1-2 hrs
abs alcohol 2 - 1-2 hrs
abs alcohol 3 - 1-2 hrs

109
Q

dehydration time if flemming’s fluid is used

running water -
alcohol 30 % -
alcohol 50 % -
alcohol 70 % -
alcohol 90 % -
absolute alcohol 1
abs alcohol 2
abs alcohol 3

A

running water - 1-12 hrs
alcohol 30 % - 30mns - hrs
alcohol 50 % - 30 mns - 3 hrs
alcohol 70 % - 30 mns - 3 hrs
alcohol 90 % - 1-3 hrs
absolute alcohol 1 - 1-2 hrs
abs alcohol 2 - 1-2 hrs
abs alcohol 3 - 1-2 hrs

110
Q
A

Hpct (18 decks)

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