HISTOPATH: DEHYDRATION

Dehydration is a process of removing intercellular and extracellular water from the tissue following fixation and prior to wax impregnation and to remove the fixative and water from the tissue and replace them with dehydrating fluid

• True
• False

Starting concentration for delicate tissues (embryonic tissues)

• 30% ethanol
• 90% ethanol:

Dehydration should not be _______ the volume of the tissue

• less than 10 times
• more than 10 times

Tend to harden only the surface of the tissue

• concentrated alcohols
• unconcentrated alcohols

Characteristics of an Ideal Dehydrating Solution:

• Dehydrate rapidly without producing considerable shrinkage or distortion of tissues
• Does not evaporate very fast
• Be able to dehydrate fatty tissues
• Does not harden tissues excessively

Strength of initial alcohol required in each concentration will depend on:

• Size of the tissue
• Nature of the tissue
• Fixative used

Will hasten dehydration time; for tissue sections that require urgent examinations

• 37℃
• Anhydrous copper sulfate
• Blue discoloration of copper sulfate crystals

Ensure complete dehydration

• 37℃
• Anhydrous copper sulfate
• Blue discoloration of copper sulfate crystals

Indicate full saturation of dehydrating fluids with water

• 37℃
• Anhydrous copper sulfate
• Blue discoloration of copper sulfate crystals

Recommended for routine dehydration of tissues ▪ the best dehydrating agent ▪ fast-acting, mixes with water and many organic solvents, and penetrates tissues easily

• Ethyl alcohol (ethanol)
• Methyl alcohol
• Butyl alcohol