MEDL 310 - TISSUE PROCESSING
At what temperature should wax be monitored at and why is this important? - ✔️✔️2-
4C above its melting point. High temperature will damage tissue and affect cutting
characteristics of the wax.
What is the results of leaving tissue in dehydrating alcohols or clearing agents for
extended periods of time? What is the remedy? - ✔️✔️Tissue will be hard, shrunken,
and difficult to section. Nothing can be done except to obtain a fresh sample if available
When is it necessary to wash tissues? - ✔️✔️After the use of dichromate-containing
fixatives or zinc formalin
Name the BEST dehydrant - ✔️✔️ethanol
Name the BEST substitute if the best dehydrant cannot be used. - ✔️✔️isopropanol
Define universal solvent, give 3 examples. - ✔️✔️A solution that performs both
dehydration and clearing steps of processing. Examples = dioxane, tertiary butanol, and
tetrahydrofuran
Give 6 reasons dehydration may be inadequate - ✔️✔️If tissues are dehydrated too
quickly, if tissue is too thick, if too many pieces are processed in the same cassette,
alcohol concentration is inaccurate or alcohol is contaminated, or if tissue is not
completely immersed.
State the 2 substances that a clearing agent must be miscible with. - ✔️✔️Alcohol and
paraffin wax
List 4 clearing agents - ✔️✔️xylene, toluene, benzene, chloroform
What is the most commonly used clearing agent? - ✔️✔️xylene.
What is the result of inadequate dehydration or clearing? What is the remedy? -
✔️✔️Infiltration will be insufficient; tissue will be soft and mushy. Remove wax and
repeat from step which was inadequate.
Define dehydration. - ✔️✔️the gradual removal of water from tissues
List 6 common errors that may occur when clearing tissues during processing. -
✔️✔️inadequate time in clearing agent, if tissue is too thick, too many pieces are
processed in same cassette, inadequate dehydration, clearing agent is contaminated, or
tissues are not completely immersed.
At what temperature should wax be monitored at and why is this important? - ✔️✔️2-
4C above its melting point. High temperature will damage tissue and affect cutting
characteristics of the wax.
What is the results of leaving tissue in dehydrating alcohols or clearing agents for
extended periods of time? What is the remedy? - ✔️✔️Tissue will be hard, shrunken,
and difficult to section. Nothing can be done except to obtain a fresh sample if available
When is it necessary to wash tissues? - ✔️✔️After the use of dichromate-containing
fixatives or zinc formalin
Name the BEST dehydrant - ✔️✔️ethanol
Name the BEST substitute if the best dehydrant cannot be used. - ✔️✔️isopropanol
Define universal solvent, give 3 examples. - ✔️✔️A solution that performs both
dehydration and clearing steps of processing. Examples = dioxane, tertiary butanol, and
tetrahydrofuran
Give 6 reasons dehydration may be inadequate - ✔️✔️If tissues are dehydrated too
quickly, if tissue is too thick, if too many pieces are processed in the same cassette,
alcohol concentration is inaccurate or alcohol is contaminated, or if tissue is not
completely immersed.
State the 2 substances that a clearing agent must be miscible with. - ✔️✔️Alcohol and
paraffin wax
List 4 clearing agents - ✔️✔️xylene, toluene, benzene, chloroform
What is the most commonly used clearing agent? - ✔️✔️xylene.
What is the result of inadequate dehydration or clearing? What is the remedy? -
✔️✔️Infiltration will be insufficient; tissue will be soft and mushy. Remove wax and
repeat from step which was inadequate.
Define dehydration. - ✔️✔️the gradual removal of water from tissues
List 6 common errors that may occur when clearing tissues during processing. -
✔️✔️inadequate time in clearing agent, if tissue is too thick, too many pieces are
processed in same cassette, inadequate dehydration, clearing agent is contaminated, or
tissues are not completely immersed.
