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Hpct > LEC 9 - DEHYDRATION > Flashcards

LEC 9 - DEHYDRATION Flashcards

1
Q
A
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2
Q

dehydration is a Process of removing intercellular and extracellular ______
from the tissue following fixation and prior to wax impregnation

A

water

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3
Q

is the removal of water by EVAPORATION from a solid,
semi-solid or liquid

A

Drying

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4
Q

Solid tissues should never be allowed to air dry

true or false

A

true

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5
Q

involves slow substitution of the water in the
tissue with an organic solvent

A

Dehydration

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6
Q

Most dehydrating agents are strong organic solvents that bring about some ___ and ___ of cell components

A

shrinkage and extraction

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7
Q

how to prevent the shrinkage and extraction of cell components in dehydration caused by being a strong organic solvent

A

To minimize these effects, dehydrating agents are used in a graded series for short periods of time, and water is gradually replaced so that violent osmotic changes do not produce distortions

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8
Q

CHARACTERISTICS OF AN IDEAL DEHYDRATING
SOLUTION

A

➔ It must dehydrate rapidly without producing considerable shrinkage or distortion of tissues
➔ Not evaporate very fast
➔ Be able to dehydrate fatty tissues
➔ It should not harden the tissue excessively
➔ It should not remove stains
➔ Not toxic to the body
➔ Not be a fire hazard

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9
Q

general rule in dehydration

A

, whatever dehydrating agent is used, the
amount in each step should not be less than 10 times the volume of the tissue in order to ensure complete penetration of the tissue by the dehydrating solution

It is also important to keep the dehydration times as brief as possible to minimize the risk of extracting cellular components

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10
Q

FACTORS TO CONSIDER IN DEHYDRATION

A

size and nature of the tissue: 30%
type of fixative used
temperature -
ratio

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11
Q

temperature for dehydration that hastens the dehydration time and is used specially for tissue sections that require urgent examination

A

37*C

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12
Q

an example of process wherein we are using 37*C for faster dehydration time

A

fragmentary biopsies

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13
Q

perfect ratio for dehydration

A

not less than 10x the tissue sample

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14
Q

To ensure complete dehydration:

A

A layer of anhydrous copper sulfate, about ¼ inch deep is placed in the bottom of the container and covered with filter
paper

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15
Q

what is the purpose of anhydrous copper sulfate in dehydration

A

This will accelerate dehydration by removing water from the dehydrating fluid

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16
Q

Blue discoloration of copper sulfate crystals =

A

full saturation of dehydrating fluids with water

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17
Q

example of alcohol as a dehydrating agents

A

ethyl alcohol (ethanol)
methyl
butyl tertiary
isoprophyl
pentanol (arnyl alcohol)

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18
Q

boiling point of ethanol

A

78.3 * C

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19
Q

can ethanol and wax mix?

A

they can’t

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20
Q

in using ethanol

Advisable to remove water gently and allow the tissue to slowly adjust to its removal
○ The more delicate the tissue, the more gently this should be done, but there is no hard and fast rule

true or false

A

true

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21
Q
A
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22
Q

is ethanol toxic?

A

no

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23
Q

ethanol is miscible in all proportions with water

t or f

A

true

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24
Q

used For routine dehydration of tissue

A

ethanol

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25
Q

best dehydrating agent (fast acting)

A

ethanol

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26
Q

For delicate tissues, particularly for embryonic
tissues, dehydration starting with ___ethanol is recommended

A

30%

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27
Q

can we use ethanol in eyes and embryos

A

yes

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28
Q

can ethanol Mixes with water and many organic solvents and is Reliable

A

yes

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29
Q

Appears to cause less extraction of cellular components
in general than other agents

A

ethanol

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30
Q

● Penetrates tissues easily
● Not poisonous
● Inexpensive and easily obtained

A

ethanol

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31
Q

Long periods in absolute ethanol will cause

A

excessive
shrinkage and hardening

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32
Q

ethanol Extracts __ from
sections

A

methylene blue and other thiazine dyes

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33
Q

ethanol Extracts more lipids than __

A

acetone

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34
Q

Primarily employed for blood and tissue films and for
smear preparation

A

methyl alcohol

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35
Q

Boiling point of butyl alcohol

A

117.7 *C

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36
Q

Utilized in plant and animal micro-technique
● Slow dehydrating agent

A

butyl alcohol

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37
Q

advantage of butyl alcohol

A

● Less shrinkage and hardening than with ethyl
● Excellent for slow processing
● Miscible with paraffin

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38
Q

can butanol and wax mix>

A

yes

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39
Q

DISADVANTAGES of butyl alcohol

A

● Odorous
● Slow-acting
● Long periods of infiltration necessary
● Dehydrating power low

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40
Q

Boiling point of tertiary butanol

A

82.8 * C

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41
Q

Universal solvent

A

tertiary butanol

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42
Q

act as dehydrating and clearing agent

A

tertiary butanol

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43
Q

May be used in staining series as a dehydrating agent

A

tertiary butanol

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44
Q

Mixes with water, ethanol, xylene and paraffin in all

A

tertiary butanol

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45
Q

DISADVANTAGES of tertiary butanol

A

● Odorous
● More expensive than butanol
● Primary infiltration must be done in half tertiary butanol
and half paraffin, prior to paraffin impregnation
● Reagent tends to solidify at room temperature or below
25°C

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46
Q

boiling point of ISOPROPYL ALCO

A

82.3*C

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47
Q

no government restriction on its use

A

isopropyl alcohol

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48
Q

● Sufficiently water-free to use in place of absolute ethanol

A

isopropyl alcohol

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49
Q

“The best all-around substance for ethyl alcohol”

A

isopropyl alcohol

50
Q

Less expensive than tax-free alcohol

A

isopropyl alcohol

51
Q

Cannot be used in the celloidin technique since nitrocellulose is insoluble in it

A

isopropyl

52
Q

Cannot be used for preparing staining solutions, since
dyes are not soluble in it

A

isopropyl

53
Q

Boiling point of pentanol

A

Boiling point: 128°C

54
Q

pentanol is also called

A

arnyl alcohol

55
Q

pentanol is miscible in what substances

A

Miscible with 90% alcohol, toluene and xylene

56
Q

this alcohol dissolves paraffin wax

A

pentanol (arnyl alcohol )

57
Q

● Toxic
● Cannot be used in poorly ventilate rooms
● Not miscible with water

A

pentanol (arnyl alcohol )

58
Q

the strength of the initial alcohol required will depend upon the ___

A

size and nature of each tissue and fixative used

59
Q

A very concentrated solution (above 80%) makes tissues

A

hard, brittle and difficult to cut

60
Q

85-95% of alcohol concentration is liable to produce____

A

shrinkage and hardening of tissues leading to distortion

61
Q

above 80% of alcohol concentration is liable to produce____

A

hard, brittle, and difficult to cut

62
Q

95% - absolute of alcohol concentration is liable to produce____

A

hard tissue surface but the deeper parts are unpenetrated

63
Q

result of 95% -absolute used of alcohol at starter will caused in tissue impregnation and cutting

A

UNEQUAL impregnation of tissues with consequently
POOR CUTTING of section

64
Q

how to avoid the consequences of using 95%-absolute alcohol as a starter

A

To avoid this, 70% or lower concentrations of alcohol,
gradually increased to 95% are used

65
Q

Prolonged storage in lower concentration (below 70%)tends to __the tissue

A

macerate

66
Q

DEHYDRATION SEQUENCE FOR SPECIMENS (NOT MORE
THAN 4MM THICK)

A
  1. 70% ethanol, 15 minutes
  2. 90% ethanol, 15 minutes
  3. 100% ethanol, 15 minutes
  4. 100% ethanol, 15 minutes
  5. 100% ethanol, 30 minutes
  6. 100% ethanol, 45 minute
67
Q

boiling point of acetone

A

56*C

68
Q

Cheap, rapid acting dehydrating agent utilized for most
urgent biopsies

A

acetone

69
Q

acetone Dehydrates in __ to __ hours

A

½ to 2

70
Q

is acetone Clear, colorless

A

yes

71
Q

can acetone Mixes with water, ethanol and most organic solvents

A

yes

72
Q

More miscible with EPOXY RESINS than alcohol but highly flammable and extremely volatile fluid

A

acetone

73
Q

Limited only to small pieces of tissues due to its
extreme volatility and inflammability

A

acetone

74
Q

Rapid in action but penetrates tissues poorly and causes
brittleness in tissues that are prolonged dehydrate

A

acetone

75
Q

Most lipids are removed

A

acetone

76
Q

Produces considerable tissue shrinkage
* Not recommended for routine dehydration purposes

A

acetone

77
Q

Does not extract methylene blue and other dyes from
stained sections

A

acetone

78
Q
  • May cause less shrinkage of specimen than ethanol
  • Not reactive with OsO4 remaining in specimen
  • Miscible with most embedding resins
A

acetone

79
Q

do acetone Requires a clearing agent

A

yes

80
Q

volume needed for acetone

A

must be 20 times the tissue

81
Q

best processing of acetone needs _

A

Best processing requires a graded series of a mixture of
acetone and xylene before one can go into paraffin

82
Q
  • Needs good ventilation
  • Evaporates rapidly
  • Flammable
A

acetone

83
Q
  • Absolute acetone is easily contaminated with water,
    resulting in __
A

complete dehydration

84
Q

substances that are only soluble in
dilute solutions of acetone

A

Uranyl acetate and phosphotungstic acid

85
Q

Refractive index of dioxane (diethylene dioxide)

A

1.42

86
Q

boiling point of dioxane (diethylene dioxide)

A

101.5*C

87
Q

Excellent dehydrating and clearing agent

A

Dioxane (Diethylene Dioxide)

88
Q

Tissues can be left for long periods of time without affecting
the consistency or staining properties of the specimen

A

dioxane (diethylene dioxide )

89
Q

Tissue sections dehydrated with dioxane tend to __poorly

A

ribbon
poorly

90
Q

Universal solvent – it dehydrates and clears

A

Dioxane (Diethylene Dioxide)

91
Q

Costs about four times more than absolute alcohol

A

Dioxane (Diethylene Dioxide)

92
Q

Graupner’s Method
(Time Schedule for Dehydration with Dioxane)

A
  • (1st) Pure dioxane solution = 1 hour
  • (2nd) Pure dioxane solution = 1hour
  • (3rd) Pure dioxane solution = 2 hours
  • 1st Paraffin wax = 15 minutes
  • 2nd Paraffin wax = 45 minutes
  • 3rd Paraffin Wax = 2 hours
  • Embed in mold and in cool water
93
Q

Tissue is wrapped in gauze bag suspended in dioxane solution and a little anhydrous calcium oxide

A

Weiseberger’s Method

94
Q

Water is displaced from the tissue by dioxane and in turn absorbed by calcium oxide or quicklime

A

Weiseberger’s Method

95
Q

dehydration time using Weiseberger’s Method

A

3-24 hrs

96
Q

Tissue fixed in chromate fixative, e.g.,____
fluid must be washed in running tap water prior to treatment
with dioxane in order to remove the chromate

A

Regaud’s or Moller’s

97
Q
  • Boiling point of cellosolve
A

156.4*C

98
Q

The tissue may be transferred from water or normal saline
directly to __and stored in it for months without
producing hardening or distortion

A

cellosolve

99
Q

Ethylene glycol ether is combustible at what temperature

A

110°F and 120*F

100
Q

Following exposure, the reproductive, fetal, urinary and blood systems are particularly vulnerable to their
toxic side effects

A

Cellosolve
(Ethylene Glycol Monoethyl Ether)

101
Q

Boiling point pf triethyl phosphate

A

215*C

102
Q

Removes water very readily

A

triethyl phosphate

103
Q

Used to dehydrate sections and smear

A

triethyl phosphate

104
Q

It both dehydrates and clears tissues since it is miscible in
water and paraffin

A

Tetrahydrofuran (THF)

105
Q

Can dissolve many substances including fats and is in itself miscible with lower alcohols, ether, chloroform, acetone,
benzene and xylene

A

Tetrahydrofuran (THF)

106
Q

It may be used for demixing, clearing, and dehydrating
paraffin section before and after staining

A

Tetrahydrofuran (THF)

107
Q

It does not dissolve aniline dyes

A

tetrahydrofuran

108
Q

Eye and skin irritant, and prolonged exposure (up to 6
months) may cause conjunctival irritation

A

Tetrahydrofuran (THF)

109
Q

Solvents of mounting media

A

tetrahydrofuran

110
Q

Better results than most universal solvents

A

tetrahydrofuran

111
Q

Added to each 95% ethanol baths as part of dehydration
process

A

4% PHENOL

112
Q

i t acts as a softener for hard tissues

A

GLYCEROL ALCOHOL MIXTURE OR IN “MOLLIFLEX”

113
Q

Tissue processing for ___is commonly accomplished using ethanol as a
dehydrating solvent and propylene oxide as a transition fluid

A

transmission electron microscopy
(TEM)

114
Q

Tissue processing for transmission electron microscopy
(TEM) is commonly accomplished using ethanol as a
dehydrating solvent and ____ as a transition fluid

A

propylene oxide

115
Q

__is a good substitute for propylene oxide

A

Acetonitrile

116
Q

is acetonitrile carcinogenic?

A

no

117
Q

this DA for electron microscopy that Does not interfere with epoxy polymerization

A

acetonitrile

118
Q

Resulting cured resins have excellent cutting quality and
beam stability

A

acetonitrile

119
Q

Also used as a dehydrating agent for cells prepared for
scanning electron microscopy (SEM)

A

acetonitrile

120
Q
A

Hpct (18 decks)

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