LESSON 4: DEHYDRATION

Question 1

 Removal of fixative and intercellular and extracellular water from tissues in preparation for infiltration

Answer 1

DEHYDRATION

Question 2

 Increasing strengths of the dehydrating agent is used to prevent distortion of tissue structures by diffusion currents (flow of molecules)

Answer 2

DEHYDRATION

Question 3

 DELICATE TISSUES (eg. embryo): start with

Answer 3

30% ethanol up to 70%

Question 4

 NORMAL TISSUES: start with

Answer 4

70% up to 95% or Absolute alcohol

Question 5

VOLUME: [?] the volume of tissue

Answer 5

10X

Question 6

Prolonged Immersion
High Concentrations: tissues become
Low Concentrations: tissues become

Answer 6

hard and brittle

macerated

Question 7

: increases rate of dehydration and used for tissues that require urgent examination

Answer 7

37 deg Celsius

Question 8

 Accelerates diffusion of molecules increasing the rate of dehydration

Answer 8

Agitation

Question 9

: ¼ inch at the bottom of the container to facilitate the removal of water molecules from the dehydrating fluid

Answer 9

**Anhydrous copper sulfate

Question 10

 Clear, colorless, flammable liquid

Answer 10

ETHANOL

Question 11

 Recommended for routine dehydration

Answer 11

ETHANOL

Question 12

 Best dehydrating agent, fast-acting and miscible in water and many organic solvents

Answer 12

ETHANOL

Question 13

 Penetrates tissues easily

Answer 13

ETHANOL

Question 14

 Not poisonous, not very expensive

Answer 14

ETHANOL

Question 15

 Long Immersion in high concentrations should be avoided

Answer 15

ETHANOL

Question 16

 Substitute for ethanol

Answer 16

ISOPROPYL ALCOHOL

Question 17

 Also referred to as wood alcohol

Answer 17

METHANOL

Question 18

 Toxic dehydrating agent ( is converted to formaldehyde and can be further converted to formic acid: both formaldehyde and formic acid are toxic to the body)

Answer 18

METHANOL

Question 19

 for blood & tissue films and smear preparations

Answer 19

METHANOL

Question 20

 Slow-acting

Answer 20

BUTYL ALCOHOL

Question 21

 For plants & animals

Answer 21

BUTYL ALCOHOL

Question 22

 Also recommended for tissues which do not require rapid processing

Answer 22

BUTYL ALCOHOL

Question 23

 May be used in combination with ethanol

Answer 23

BUTYL ALCOHOL

Question 24

 Used to dehydrate slides after staining

Answer 24

BUTYL ALCOHOL

Question 25

 cheap, rapid and used for most urgent biopsies

Answer 25

ACETONE

Question 26

 duration: 30 minutes to 2 hours

Answer 26

ACETONE

Question 27

 removes lipids from tissues

Answer 27

ACETONE

Question 28

 penetration is poor and causes brittleness

Answer 28

ACETONE

Question 29

 Rapid and does not cause any harmful effect on tissues

Answer 29

CELLOSOLVE (Ethylene Glycol Monoethyl Ether)

Question 30

 4 baths: 30 min > 30-60 min > 60 min > 90 min

Answer 30

CELLOSOLVE (Ethylene Glycol Monoethyl Ether)

Question 31

 Toxic to the reproductive, fetal, urinary and blood systems

Answer 31

CELLOSOLVE (Ethylene Glycol Monoethyl Ether)

Question 32

 Combustible at 110-120 OF

Answer 32

CELLOSOLVE (Ethylene Glycol Monoethyl Ether)

Question 33

 Propylene-based glycol ethers may be used in place of EGME

Answer 33

CELLOSOLVE (Ethylene Glycol Monoethyl Ether)

Question 34

 Excellent dehydrating and clearing agent

Answer 34

DIOXANE (Diethylene dioxide)

Question 35

DIOXANE (Diethylene dioxide): **dehydration and clearing may be done at the same time using dioxane

Answer 35

 Fixatives  Dioxaneparaffin

Question 36

 Sections ribbon poorly

Answer 36

DIOXANE (Diethylene dioxide)

Question 37

 Expensive and extremely dangerous

Answer 37

DIOXANE (Diethylene dioxide)

Question 38

 Vapor tends to accumulate in the body and is highly toxic

Answer 38

DIOXANE (Diethylene dioxide) DIOXANE (Diethylene dioxide)

Question 39

 Creates explosive peroxides

Answer 39

DIOXANE (Diethylene dioxide)

Question 40

 Removal of water

Answer 40

DIOXANE (Diethylene dioxide)

Question 41

: uses several changes of pure dioxane

Answer 41

 Graupner’s Method

Question 42

: uses pure dioxane and anhydrous calcium oxide or quicklime to facilitate removal of water

Answer 42

 Weiseberger’s Method

Question 43

 May be used as dehydrating and clearing agent THF (Tetrahydrofuran)

Answer 43

THF (Tetrahydrofuran)

Question 44

 Can dissolve fats in tissues

Answer 44

THF (Tetrahydrofuran)

Question 45

 Vapors cause nausea, dizziness, headache and anesthesia

Answer 45

THF (Tetrahydrofuran)

Question 46

 Skin and eye irritant

Answer 46

THF (Tetrahydrofuran)

Question 47

 Offensive odor; may cause conjunctivitis during prolonged exposure

Answer 47

THF (Tetrahydrofuran)

Question 48

 May be used to dehydrate sections and smears after staining

Answer 48

TRIETHYL PO4

Question 49

: added to 95% alcohol to soften tissues

Answer 49

 4% phenol

Question 50

: used to soften hard tissues

Answer 50

 Glycerol-alcohol mixture and Molliflex