Dehydration

Question 1

Removes intercellular and extracellular water from tissue after fixation and before wax infiltration

Answer 1

Dehydration (Tissue Processing)

Question 2

Solvents used to remove water, typically alcohols; dehydration is done using ascending grades (70% -> absolute)

Answer 2

Dehydrating Agents/Dehydrants

Question 3

Initial concentration of 70% for routine tissues and 30% for delicate tissues; amount of dehydrating agent is at least 10x; room temperature is used

Answer 3

Dehydration Process

Question 4

Widely used dehydrating agent

Answer 4

Alcohol

Question 5

Boiling point: 78.3°C; recommended for routine dehydration; considered the best dehydrating agent; clear, colorless, flammable fluid; fast-acting; mixes with water and many solvents; penetrates tissue easily; not poisonous; expensive

Answer 5

Ethanol

Question 6

Primarily used for blood and tissue films, and for smear preparations; toxic (can cause blindness and death)

Answer 6

Methanol

Question 7

Boiling point: 117.7°C; utilized in plant and animal microtechniques; slow-acting but causes less shrinkage; odorous

Answer 7

Butanol

Question 8

Boiling point: 82.8°C; universal solvent; dehydrates and clears

Answer 8

Tertiary Butanol

Question 9

Boiling point: 128°C; miscible with 90% alcohol, toluene, xylene; dissolves paraffin

Answer 9

Pentanol

Question 10

Boiling point: 82.3°C; excellent substitute for ethanol; not for preparing staining solutions; best clearing agent for microwave techniques

Answer 10

Isopropanol

Question 11

Ensures complete dehydration; accelerates dehydration by removing water from the dehydrant; blue color indicates presence of water

Answer 11

Anhydrous CuSO4

Question 12

Clear, colorless liquid; highly miscible, flammable; cheap and rapid-acting; dehydrates in 0.5-2 hours; can cause shrinkage and brittleness; removes lipids; not recommended

Answer 12

Acetone

Question 13

Also known as diethylene dioxide; serves as both dehydrating and clearing agent; miscible with paraffin, alcohol, xylene; produces less tissue shrinkage; tissues can be stored here for a long period; disadvantages: expensive, tissues ribbon poorly, highly toxic

Answer 13

Dioxane

Question 14

Uses pure dioxane and paraffin

Answer 14

Graupner’s Method (Dioxane Dehydration)

Question 15

Tissue is wrapped in gauze and suspended in dioxane with anhydrous calcium oxide/quicklime

Answer 15

Weiseberger’s Method (Dioxane Dehydration)

Question 16

Also known as ethylene glycol monoethyl ether; rapid dehydrating agent; tissues can be stored long-term without distortion; dangerous: combustible and has toxic side effects

Answer 16

Cellosolve

Question 17

Removes water readily; produces very little distortion and hardening; used to dehydrate sections and smears after certain stains; produces minimal shrinkage

Answer 17

Tri-Ethyl Phosphate

Question 18

Universal solvent; acts as both a dehydrating and clearing agent; dissolves many substances, including fats; used for demixing, clearing, and dehydrating paraffin sections; improves most staining procedures; toxic if ingested or inhaled; offensive odor; can cause conjunctival irritation; should be used in a well-ventilated room

Answer 18

Tetrahydrofuran

Question 19

Dehydrate and clear simultaneously; examples include dioxane, tertiary butanol, and tetrahydrofuran

Answer 19

Universal Solvents

Question 20

Dehydrating agent for transmission electron microscopy (EM)

Answer 20

Ethanol (for EM)

Question 21

Toxic and carcinogenic; acts as a transition fluid to facilitate resin infiltration

Answer 21

Propylene Oxide

Question 22

Substitute for propylene oxide in electron microscopy

Answer 22

Acetonitrile