dehydration and clearing Flashcards

1
Q

process of removing intercellular and extracellular water from the tissue following fixation and prior to wax impregnation

A

dehydration

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2
Q

removal of water by evaporation from solid, semi-solid, or liquid state

A

drying

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3
Q

10% formalin and Bouin’s

1) 70% - 100& alcohol III = __ - __ hours

2) xylol I = __ - __ hours

3) xylol II = __ hour

A

1) 3-12 hours

2) 1-2 hours

3) 1 hour

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4
Q

characteristics of an ideal dehydrating agent

A
  1. should dehydrate rapidly without shrinkage or distortion of tissue
  2. should not evaporate very fast
  3. should be able to dehydrate even fatty tissue
  4. should not harden tissues excessively
  5. should not remove stains
  6. should not be toxic to the body
  7. should not be a fire hazard
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5
Q

commonly used dehydrating agents

A

alcohol - most commonly used
acetone
dioxane
cellosolve
triethyl phosphate
tetrahydrofuran

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6
Q

____ ____is the recommended dehydrating agent for routine dehydration. considered to be the best dehydrating agent because it is ___ ___.

A

ethyl alcohol, fast-acting

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7
Q

___ toxic dehydrating agent, primarily employed for blood and tissue films and for smear preparation

A

methyl alcohol

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8
Q

___ is a slow dehydrating agent, produce less shrinkage and hardening than ethyl alcohol. recommended for tissues that do not require rapid processing

A

butyl alcohol

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9
Q

___ is a cheap dehydrating agent utilized for urgent biopsies which dehydrate in 1/2 to 2 hours. It is a clear, colorless fluid that mixes with water, ethanol, and most organic solvents

A

acetone

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10
Q

___ is a excellent dehydrating and clearing agent that is readily miscible in water, melted paraffin, alcohol, and xylol.it produces less tissue shrinkage than alcohol. however, it is extremely dangerous

A

dioxane

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11
Q

___ dehydrates rapidly. tissues may be transferred from water or saline directly to cellosolve and stored for months without producing hardening or distortion.

A

cellosolve

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12
Q

___ removes water readily and produce very little distortion and hardening of tissue

A

triethyl phosphate

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13
Q

___ reagent that both dehydrates and clears tissue since it is miscible in both water and paraffin.

A

tetrahydrofuran

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14
Q

two types of clearing agents: ___ and ___

A

organic solvents and oils

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15
Q

___ clearing of choice

A

xylol

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16
Q

characteristics of a good clearing agent

A

should be miscble with alchol
should be miscible with 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

17
Q

__ most commonly used in histology laboratories. clearing time is usually __ - __ hour/s. used for clearing, embedding, and mounting procedures.

A

xylene, 1/2 - 1 hour

18
Q

___ is used as an substitute for xylne or benzene for clearing both during embedding and mounting process. time recommended for clearing is __ - __ hours

A

toluene. 1-2 hours

19
Q

__ preferred by some since it penetrates and clear tissues rapidly. recommended for urgent biopsies and routine purposes

A

benzene

20
Q

___ is slower than xylene but causes less brittleness. thicker tissue blocks can be processed. used when tough tissues like skin, fibroid, and decalcified tissues.

A

chloroform

21
Q

___ used to clear both paraffin and celloidin sections. recommended for CNS tissues and cytological studies particularly smooth muscles and skin. clearing is usually complete in __ - __ days

A

cedarwood oil, 2-3 days

22
Q

not normally utilized but is recommended for embryos, insects and delicate specimens due to its ability to clear 70% alcohol without excessive tissue shrinkage and hardening.

A

aniline oil

23
Q

__ quality is not guaranteed due to tendency to become adulterated.

A

clove oil

24
Q

similar to chloroform but cheaper. dangerous to inhale on prolonged exposure

A

carbon tetrachloride

25
Q

slow acting clearing agent that can be used when double embedding techniques are required

A

methyl benzoate and methyl salicylate