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11 Cards in this Set
- Front
- Back
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Defined as killing, penetration, and hardening of tissues |
Fixation |
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First and most critical step in tissue processing |
Fixation |
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What is the primary purpose of fixation? |
Preserve the morphologic and chemical integrity of the cell in a life-like manner as possible |
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What are the effects of fixatives |
● Hardens soft tissues in preparation for further tissue processing ● Render cells resistant to damage caused by chemicals used in further processing ● Inhibit decomposition caused by bacteria and fungi ● Minimize the risk of occupational infection ● Act as mordant for certain stains, thus promoting or hastening staining, or inhibit certain dyes ● Reduce the risk of infections during handling and actual processing of tissues |
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Characteristics of a Good fixative |
● Cheap ● Stable ● Safe ● Quick ● Inhibits bacterial decomposition ● Produce minimum shrinkage ● Rapid and even penetration ● Hardens the tissue ● Makes cellular contents resistant to further processing ● Permit staining |
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Factors of affecting fixation |
-fixative of choice -time -tissue-fixative ratio -Penetration rate -thickness of specimen -tissue components -pH -temperature -Osmolality -agitation, vacuum |
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What is the fixative of choice in fixation? |
10 % neutral buffered formalin |
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In time, must be performed as soon as possible; __-__ after blood supply is cut off |
20-30 mins |
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What is the tissue-to-fixative ratio |
1:10 or 1:20 |
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What is the tissue-to-fixative ratio |
1:10 or 1:20 |
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In penetration rate, formalin: |
1mm/hr |
