LESSON 4: DEHYDRATION Flashcards
Removal of fixative and intercellular and extracellular water from tissues in preparation for infiltration
DEHYDRATION
Increasing strengths of the dehydrating agent is used to prevent distortion of tissue structures by diffusion currents (flow of molecules)
DEHYDRATION
start with 70% up to 95% or Absolute alcohol
NORMAL TISSUES:
start with 30% ethanol up to 70%
DELICATE TISSUES
What should be the volume of tissue?
10X
High Concentrations: tissues become hard and brittle
Low Concentrations: ____________
tissues become macerated
What temperature increases rate of dehydration and used for tissues that require urgent examination
37C
Accelerates diffusion of molecules increasing the rate of dehydration
Agitation
How much Anhydrous copper sulfate should be place at the bottom of the container to facilitate the removal of water molecules from the dehydrating fluid?
1/4
What are the most common alcohol dehydrants?
ETHANOL
ISOPROPYL ALCOHOL
METHANOL
BUTYL ALCOHOL
What dehydrating agent is a Clear, colorless, flammable liquid that is Recommended for routine dehydration?
Ethanol
Best dehydrating agent, fast-acting and miscible in water and many organic solvents
ETHANOL
What dehydrating agent is being described?
✓ Penetrates tissues easily
✓ Not poisonous, not very expensive
✓ Long Immersion in high concentrations should be avoided
Ethanol
Substitute for ethanol and can be used for for blood & tissue films and smear preparations
ISOPROPYL ALCOHOL
Also referred to as wood alcohol
METHANOL
Toxic dehydrating agent (methanol is converted to formaldehyde and can be further converted to formic acid: both formaldehyde and formic acid are toxic to the body)
METHANOL
It is a slow acting dehydrating agent that can be used for plants and animals for.
Butyl Alcohol
This dehydrating agents is recommended for tissues which do not require rapid processing
BUTYL ALCOHOL
What dehydrating agent is being described?
✓ May be used in combination with ethanol
✓ Used to dehydrate slides after staining
Butyl Alcohol
✓ cheap, rapid and used for most urgent biopsies
✓ duration: 30 minutes to 2 hours
✓ removes lipids from tissues
✓ penetration is poor and causes brittleness
ACETONE
Rapid and does not cause any harmful effect on tissues
CELLOSOLVE (Ethylene Glycol Monoethyl Ether)
How many baths do cellosolve use?
4 baths
Toxic to the reproductive, fetal, urinary and blood systems and combustible at 110-120C
CELLOSOLVE (Ethylene Glycol Monoethyl Ether)
based glycol ethers may be used in place of EGME
Propylene
Excellent dehydrating and clearing agent
DIOXANE (Diethylene dioxide)
What dehydrating agent is being described?
✓ Sections ribbon poorly
✓ Expensive and extremely dangerous
✓ Vapor tends to accumulate in the body and is highly toxic
✓ Creates explosive peroxides
✓ Removal of water
Dioxane
uses several changes of pure dioxane
Graupner’s Method
uses pure dioxane and anhydrous calcium oxide or quicklime to facilitate removal of water
Weiseberger’s Method
May be used as dehydrating and clearing agent and Can dissolve fats in tissues
THF (Tetrahydrofuran)
What dehydrating agent is being described?
✓ Vapors cause nausea, dizziness, headache and anesthesia
✓ Skin and eye irritant
✓ Offensive odor; may cause conjunctivitis during prolonged exposure
THF (Tetrahydrofuran)
May be used to dehydrate sections and smears after staining
TRIETHYL PO4
added to 95% alcohol to soften tissues
4% phenol
used to soften hard tissues
Glycerol-alcohol mixture and Molliflex
What are the 2 additives to dehydrants?
4% phenol
Glycerol-alcohol mixture and Molliflex
