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Histopathology > 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 in dehydration?

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:
1. not dehydrate rapidly w/out producing considerable shrinkage or distortion of tissue
2. not evaporate very fast
3. not be able to dehydrate even fatty tissues
4. not harden tissues excessively
5. not remove stains
6. not be toxic to the body
7. not be a fire hazard

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8
Q

enumerate the commonly used dehydrating reagents

DSATAT

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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12
Q

dehydrating agent recommended for tissues which do not require rapid processing

A

butyl alcohol

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13
Q

why formalin-fixed tissue should not be transferred directly to higher grades of alcohol?

A

because this may produce considerable shrinkage and hardening of tissues

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14
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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15
Q

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

under dehydration topic

A

concentrated alcohols above 80%

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16
Q

prolonged storage in lower concentrations of alcohol tends to?

A

macerate the tissues

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17
Q

dehydration period using 10% formol-saline alcohol, 70% alcohol, 90%, absolute alcohol

A

13-5

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18
Q

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

A

1-12

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19
Q

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

A

13-12

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20
Q

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

A

1-6

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21
Q

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

A

1-6 hours

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22
Q

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

A

1-12

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23
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%

24
Q

time in hours for flemming’s using the absolute alcohol

A

1-3

25
Q

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

A

37C

26
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

27
Q

purpose of anhydrous copper sulfate and filter paper in dehydration

A

to accelerate dehydration by removing water from the dehydrating fluid

28
Q

blue discoloration of ___ will indicate full saturation of dehydrating fluids

A

copper sulfate crystals

29
Q

cheap, rapid-acting dehydrating agent utilized for most urgent biopsies

A

acetone

30
Q

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

A

acetone

31
Q

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

A

epoxy resins

32
Q

effect of prolonged dehydration using acetone

A

penetrates tissue poorly and causes brittleness in tissues

33
Q

these are removed from tissues with acetone

A

lipids

34
Q

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

A

diethylene dioxide

35
Q

a dehydrating agent not recommended for routine dehydration purposes

A

acetone

36
Q

advantage of dioxane

A

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

37
Q

disadvantage of dioxane

A
  • expensive
  • cumulative
  • highly toxic
38
Q

what is the method in dioxane utilizing the paraffin wax?

A

Graupner’s method

39
Q

Graupner’s method:1st pure dioxane - 1 hr2nd pure dioxane - __3rd ___ - 2 hours1st paraffin wax - 2nd paraffin wax - 3rd paraffin wax -

A

Graupner’s method:1st pure dioxane - 1 hr2nd pure dioxane - 1 hr3rd pure dioxane - 2 hrs1st paraffin wax - 15 mins2nd paraffin wax - 45 mins3rd paraffin wax - 2 hrs

40
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

41
Q

dehydration period for weiseberger’s method

A

3-24 hrs

42
Q

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

A

to remove the chromate

43
Q

this agent dehydrates rapidly

A

cellosolve (ethylene glycol monoethyl ether)

44
Q

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

A

true

45
Q

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

A

ethylene glycol ethers

46
Q

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

A

reproductive, fetal, urinary, and blood systems

47
Q

other option of ethylene glycol ethers

A

ethylene-based glycol ethers

48
Q

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

A

triethyl phosphate

49
Q

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

A

tetrahydrofuran

50
Q

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

A

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

51
Q

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

A

tetrahydrofuran

52
Q

tetrahydrofuran does not dissolve out __ dye

A

aniline dye

53
Q

prolonged exposure for this dehydrating agent may cause conjunctival irritation

A

tetrahydrofuran

54
Q

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

A

phenol (4%)

55
Q

an additive used for hard tissues

A

glycerol/alcohol mixture or in Molliflex

56
Q

enumerate the alcohol reagents

A
  • ethanol / ethyl alcohol
  • isopropanol / isopropyl alcohol
  • methanol / methyl alcohol
  • butanol / butyl alcohol
  • acetone
  • dioxane / diethylene dioxide
  • cellosolve / ethylene glycol monoethyl ether
  • triethyl phosphate
  • tetrahydrofuran
57
Q

dehydration time for acetone

A

1/2 - 2 hrs

Histopathology (16 decks)

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