DEHYDRATION

Question 1

Commonly Used Dehydrating Agents

Answer 1

A. Alcohol
B. Acetone
C. Dioxane
D. Cellosolve
E. Triethyl phosphate
F. Tetrahydrofuran

Question 2

Removal of fixative and water from the tissue

Answer 2

Dehydration

Question 3

Dehydrating time must be brief as much as possible and at a tissue-to-fixative ratio of____

Answer 3

1:10

Question 4

CHARACTERISTICS OF IDEAL DEHYDRATING SOLUTION

Answer 4

• Rapid Action, with minimal tissue shrinkage and distortion
• Should not evaporate fast
• Able to dehydrate even fatty tissues
• Should not harden tissues excessively
• Should not remove stains
• Non-toxic, and not a fire hazard

Question 5

Types of alcohol

Answer 5

Ethanol
Methanol
Butyl alcohol

Question 6

• Best dehydrant under alcohol because it is fast-acting, mixes with water (it is miscible with water) and many organic solvents, and penetrates tissues easily

Answer 6

ETHANOL

Question 7

Alcohol which is not poisonous

Not very expensive

Clear, colorless, flammable

Answer 7

Ethanol

Question 8

Alcohol

Toxic

Ideal for blood smear preparation fixation

Answer 8

Methanol

Question 9

Slow-acting alcohol

Made up of plant and animal microtechnique

Answer 9

Butyl alcohol

Question 10

• Fastest dehydrant;

will only require______ to complete the dehydration process

Answer 10

ACETONE

30 minutes to 2 hour

Question 11

Highly flammable, evaporates fast

Not recommended for routine dehydration purposes

Answer 11

Acetone

Question 12

DIOXANE
• Also known as

Answer 12

Diethylene Dioxide

Question 13

Has dual purpose

Dehydrating and clearing

Answer 13

Dioxane

tetrahydrofuran

Question 14

Wrapping tissue in gauze and suspension to a bottle containing dioxane with anhydrous calcium oxide to quicklime

Answer 14

Weiseberger’s Method

DIOXANE

Question 15

Example would be Glycol Monoethyl Ether

Answer 15

CELLOSOLVE

Question 16

Rapid, prolonged storage does not cause distortion to tissues

• Toxic inhalation, skin irritant and combustible at 110-120F
• Alternative; propylene based glycol ethers

Answer 16

Cellosolve

Question 17

• Soluble in alcohol, water, ether benzene, chloroform, acetone, and xylene

However, its disdavantage is it produces minimum shrinkage
Not commonly available in the market

Answer 17

TRIETHYL PHOSPHATE

Question 18

Advantages:
• Staining procedures are improved
• Miscible in water and paraffin wax

Disadvantages:
• Dissolve fats
• Eye and skin irritant (conjunctival irritation)

Answer 18

Tetrahydrofuran

Question 19

ADDITIVES TO DEHYDRATING AGENTS

Answer 19

• 4% Phenol
• Glycerol/alcohol mixture

Question 20

ALCOHOL
● Done in ascending grades to avoid distortion of tissue:

Answer 20

70% ROH 90% ROH 100% ROH
(absolute alcohol)

Question 21

For delicate tissues, start at

Answer 21

30%

Question 22

will hasten dehydration rate (for urgent
exams)

Answer 22

37°C

Question 23

To ensure complete dehydration:
○ Add at least ¼ deep layer of_______ at bottom of container, and cover with filter paper

○______ of________ indicates full saturation of dehydrating fluids with water. Thus alcohol must be changed with a fresh solution.

Answer 23

anhydrous Cu2SO4

Bluing

copper sulfate crystals