Fixation Flashcards

1
Q

Formalin (10 percent neutral buffered)

A

Most common fixative
A solution of formaldehyde gas in a pH balanced aqueous solution
Direct contact with the liquid or the fumes that rise from it will cause harm

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2
Q

Factors that affect fixation

A
  1. Heat- accelerates it, Cooling- slows it
  2. Dense tissue - slows it, tissues with an open, loose arrangement - penetrated quickly
  3. Ratio of fixative to tissue volume (must be 10:1)
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3
Q

Glutaraldehyde

A

Aldehyde fixative
Essentially two formaldehyde molecules linked together
Used for tissue samples that are destined for electron microscope examination (small) and is used sometimes to sterilize instruments

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4
Q

Getting rid of formalin

A

Must be recycled through specialized filtration equipment or treated with a neutralizing product to stabilize and the dispose of it through sewer system

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5
Q

Alcohol

A

Ethyl alcohol and methyl alcohol
Rarely used on their own as a fixative
Do not penetrate well and cause the tissues to become very hard and brittle
Can cause shrinkage of tissues if used on their own
Very volatile and very flammable

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6
Q

Acetic acid

A

Rarely used on its own
Causes slight swelling of tissues
Can be used with alcohol to counteract shrinkage

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7
Q

Picric acid (trinitrophenol)

A

Potentially explosive
Must be kept wet to avoid explosion
Never used on own because it causes shrinkage and penetrates poorly
Powerful yellow dye

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8
Q

Bouin’s fixative

A

Formaldehyde, acetic acid and water
Used for liver biopsies for glycogen studies

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9
Q

Mercuric chloride

A

Extremely toxic
Rarely used anymore
Highly corrosive
Used with other fixatives

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10
Q

B-5 fixative

A

Contains formaldehyde, mercuric chloride, a bigger salt and water
Used for bone marrow biopsies or lymph nodes for special studies
Must be freshly mixed before use
12-24 hours of fixation is allowed

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11
Q

B-5 substitute

A

Mercury free version
Contains zinc salt, formaldehyde, buffer salt and water
Some controversy over the success of this substitute

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12
Q

Katnovskys fixative

A

Popular for renal studues

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