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Dehydration > Dehydration > Flashcards

Dehydration Flashcards

1
Q

what is dehydration?

A

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

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2
Q

what is the purpose of dehydrating agents?

A

to remove aqueous tissue fluids with little disruption to the tissue caused by diffusion currents

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3
Q

t or f: most of the dehydrating agents are alcohols

A

true

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4
Q

dehydration starts by?

A

placing fixed specimen in 70% ethyl alcohol in water, progressing through 95% ethyl alcohol to 100% ethyl alcohol

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5
Q

recommended alcohol concentration for embryonic tissues

A

30%

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6
Q

what is the general rule?

A

the amount of dehydrating agent should not be LESS THAN 10 TIMES the volume of the tissue

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7
Q

enumerate the characteristics of an ideal dehydrating solution

A

IT SHOULD NOT:
- not dehydrate rapidly w/out producing considerable shrinkage or distortion of tissue
- not evaporate very fast
- not be able to dehydrate even fatty tissues
- not harden tissues excessively
- not remove stains
- not be toxic to the body
- not be a fire hazard

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8
Q

enumerate the commonly used dehydrating reagents

A
  • dioxane4-cellosolve
  • alcohol
  • triethyl phosphate
  • acetone
  • tetrahydrofuran
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9
Q

alcohol reco for routine dehydration of tissues, considered as the best dehydrating agent

A

ethyl alcohol (ethanol)

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10
Q

methyl alcohol is a toxic dehydrating agent primarily used for?

A
  • blood and tissue films
  • for smear preparations
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11
Q

a slow dehydrating agent utilized in plant and animal micro-techniques, producing less shrinkage

A

butyl alcohol

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11
Q

dehydrating agent recommended for tissues which do not require rapid processing

A

butyl alcohol

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12
Q

why formalin-fixed tissue be transferred directly to higher grades of alcohol?

A

because this may produce considerable shrinkage and hardening of tissues

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13
Q

these alcohols tend to harden only the surface of the tissue while the deeper parts are not completely penetrated

A

concentrated alcohols (95% or absolute)

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14
Q

this will make tissues, hard, brittle, and difficult to cut

A

concentrated alcohols above 80%

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15
Q

prolonged storage in lower concentrations of alcohol tends to?

A

macerate the tissues

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16
Q

dehydration period using 10% formol-saline

alcohol 70%
alcohol 90%
absolute alcohol

A

13-5

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17
Q

time in hours for dehydration (running water) using the zenker or helly’s fixative

A

1-12

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18
Q

dehydration (alcohol 70% to absolute) using the bouin’s fluid

A

13-12

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19
Q

dehydration (alcohol 30% to absolute) using the zenker or helly’s

A

1-6

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20
Q

dehydration (alcohol 90% to absolute) using the SUSA, Carnoy, or formol-sublimate fixative

A

1-6 hours

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21
Q

time in hours for flemming’s fluid and the dehydrating agent is running water

A

1-12

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22
Q

time in hours for flemming’s fluid is 1/2-3, what is the dehydrating agent/s that was used?

A

30%, 50%, 70%

23
Q

time in hours for flemming’s using the absolute alcohol

A

1-3

24
Q

temp what will hasten dehydration and is used for tissue sections that require urgent examinations such as fragmentary biopsies

A

37C

25
Q

to ensure complete dehydration, a layer of __ about ___ deep is placed in the bottom of the container and covered with filter paper

A

to ensure complete dehydration, a layer of ANHYDROUS COPPER SULFATE about 1/4 INCH deep is placed in the bottom of the container and covered with filter paper

26
Q

purpose of anhydrous copper sulfate and filter paper in dehydration

A

to accelerate dehydration by removing water from the dehydrating fluid

27
Q

blue discoloration of ___ will indicate full saturation of dehydrating fluids

A

copper sulfate crystals

28
Q

cheap, rapid-acting dehydrating agent utilized for most urgent biopsies which it dehydrates 1/2 to 2 hours

A

acetone

29
Q

clear, colorless fluid that mixes with water, ethanol, and most organic solvents

A

acetone

30
Q

acetone is more miscible with __ than alcohol but is highly flammable

A

epoxy resins

31
Q

prolonged dehydration using acetone

A

penetrates tissue poorly and causes brittleness in tissues

32
Q

these are removed from tissues with acetone

A

lipids

33
Q

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

A

diethylene dioxide

34
Q

a dehydrating agent not recommended for routine dehydration purposes

A

acetone

35
Q

advantage of dioxane

A

tissues can be left in this reagent for long periods without affecting the consistency or staining propertie

36
Q

disadvantage of dioxane

A
  • expensive
  • cumulative and highly toxic
37
Q

what is the method in dioxane utilizing the paraffin wax?

A

Graupner’s method

38
Q

Graupner’s method:
1st pure dioxane - 1 hr
2nd pure dioxane - __
3rd ___ - 2 hours
1st paraffin wax -
2nd paraffin wax -
3rd paraffin wax -

A

Graupner’s method:
1st pure dioxane - 1 hr
2nd pure dioxane - 1 hr
3rd pure dioxane - 2 hrs
1st paraffin wax - 15 mins
2nd paraffin wax - 45 mins
3rd paraffin wax - 2 hrs

39
Q

method used in dioxane in which the tissue is wrapped in a gauze bag and suspended in a bottle containing dioxane and a little anhydrous calcium oxide

A

Weiseberger’s method

40
Q

dehydration period for weiseberger’s method

A

3-24 hrs

40
Q

why Regaud’s or Moller’s fluid should be thoroughly washed in running tap water?

A

to remove the chromate

41
Q

this agent dehydrates rapidly

A

cellosolve (ethylene glycol monoethyl ether)

42
Q

t or f: you can store the tissue for longer periods of time using cellosolve

A

true

43
Q

combustible at 110-120F and are toxic by inhalation, skin contact, and ingestion

A

ethylene glycol ethers

44
Q

these systems can be particularly vulnerable for the toxic side effects of ethylene glycol ethers

A

reproductive, fetal, urinary, and blood systems

45
Q

other option of ethylene glycol ethers

A

ethylene-based glycol ethers

46
Q

this is used to dehydrate sections and smears following certain stains and produces minimum shrinkage

A

triethyl phosphate

47
Q

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

A

tetrahydrofuran

48
Q

tetrahydrofuran can dissolve many substances including fats and is in itself miscible with ___

A

lower alcohols, ether, chloroform, acetone, benzene, xylene

49
Q

this may be used for demixing, clearing, and dehydrating paraffin sections with fewer artifacts

A

tetrahydrofuran

50
Q

tetrahydrofuran does not dissolve out __ dye

A

aniline dye

51
Q

prolonged exposure for this dehydrating agent may cause conjunctival irritation

A

tetrahydrofuran

52
Q
A
53
Q

an additive that act as a softener for tissues such as tendon, nail, or dense fibrous tissue

A

phenol (4%)

53
Q

an additive used for hard tissues

A

glycerol/alcohol mixture or in Molliflex

Dehydration (1 decks)

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