Dehydration

Question 1

what is dehydration?

Answer 1

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

Question 2

what is the purpose of dehydrating agents?

Answer 2

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

Question 3

t or f: most of the dehydrating agents are alcohols

Answer 3

true

Question 4

dehydration starts by?

Answer 4

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

Question 5

recommended alcohol concentration for embryonic tissues

Answer 5

30%

Question 6

what is the general rule in dehydration?

Answer 6

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

Question 7

enumerate the characteristics of an ideal dehydrating solution

Answer 7

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

Question 8

enumerate the commonly used dehydrating reagents

DSATAT

Answer 8

• dioxane4
• cellosolve
• alcohol
• triethyl phosphate
• acetone
• tetrahydrofuran

Question 9

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

Answer 9

ethyl alcohol (ethanol)

Question 10

methyl alcohol is a toxic dehydrating agent primarily used for?

Answer 10

• blood and tissue films
• for smear preparations

Question 11

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

Answer 11

butyl alcohol

Question 12

dehydrating agent recommended for tissues which do not require rapid processing

Answer 12

butyl alcohol

Question 13

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

Answer 13

because this may produce considerable shrinkage and hardening of tissues

Question 14

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

Answer 14

concentrated alcohols (95% or absolute)

Question 15

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

under dehydration topic

Answer 15

concentrated alcohols above 80%

Question 16

prolonged storage in lower concentrations of alcohol tends to?

Answer 16

macerate the tissues

Question 17

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

Answer 17

13-5

Question 18

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

Answer 18

1-12

Question 19

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

Answer 19

13-12

Question 20

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

Answer 20

1-6

Question 21

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

Answer 21

1-6 hours

Question 22

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

Answer 22

1-12

Question 23

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

Answer 23

30%, 50%, 70%

Question 24

time in hours for flemming’s using the absolute alcohol

Answer 24

1-3

Question 25

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

Answer 25

37C

Question 26

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

Answer 26

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

Question 27

purpose of anhydrous copper sulfate and filter paper in dehydration

Answer 27

to *accelerate dehydration* by **removing water from the dehydrating fluid**

Question 28

blue discoloration of ___ will indicate full saturation of dehydrating fluids

Answer 28

copper sulfate crystals

Question 29

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

Answer 29

acetone

Question 30

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

Answer 30

acetone

Question 31

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

Answer 31

epoxy resins

Question 32

effect of prolonged dehydration using acetone

Answer 32

penetrates tissue poorly and causes brittleness in tissues

Question 33

these are removed from tissues with acetone

Answer 33

lipids

Question 34

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

Answer 34

diethylene dioxide

Question 35

a dehydrating agent **not recommended for routine** dehydration purposes

Answer 35

acetone

Question 36

advantage of dioxane

Answer 36

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

Question 37

disadvantage of dioxane

Answer 37

- expensive - cumulative - highly toxic

Question 38

what is the method in **dioxane** utilizing the paraffin wax?

Answer 38

Graupner's method

Question 39

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

Answer 39

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

Question 40

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

Answer 40

Weiseberger's method

Question 41

dehydration period for weiseberger's method

Answer 41

3-24 hrs

Question 42

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

Answer 42

to remove the chromate

Question 43

this agent dehydrates rapidly

Answer 43

cellosolve (ethylene glycol monoethyl ether)

Question 44

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

Answer 44

true

Question 45

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

Answer 45

ethylene glycol ethers

Question 46

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

Answer 46

reproductive, fetal, urinary, and blood systems

Question 47

other option of ethylene glycol ethers

Answer 47

ethylene-based glycol ethers

Question 48

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

Answer 48

triethyl phosphate

Question 49

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

Answer 49

tetrahydrofuran

Question 50

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

Answer 50

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

Question 51

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

Answer 51

tetrahydrofuran

Question 52

tetrahydrofuran does not dissolve out __ dye

Answer 52

aniline dye

Question 53

prolonged exposure for this dehydrating agent may cause conjunctival irritation

Answer 53

tetrahydrofuran

Question 54

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

Answer 54

phenol (4%)

Question 55

an additive used for hard tissues

Answer 55

glycerol/alcohol mixture or in Molliflex

Question 56

enumerate the alcohol reagents

Answer 56

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

Question 57

dehydration time for acetone

Answer 57

1/2 - 2 hrs