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9 Cards in this Set
- Front
- Back
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Describe the routine method for preparing paraffin sections
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1. Collecting the sample - about 1cm3
2. Fixation - formalin is used to prevent postmortem degeneration 3. Dehydration, Clearing and Embedding - alcohol washes are used to dehydrate the sample. The alcohol mus then be cleared away using a solvent (xylol or toluol), next the sample is embedded with wax 4. Sectioning - a microtome is used to slice the sample 5. Mounting and Staining - the sample is mounted on a glass slide then another solvent is used to dissolve the wax (xylol or toluol). It is then rehydrated using decreasing concentrations of alcohol and stained. Finally a slipcover is applied. |
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Describe the metric units of measurement used in microscopy
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light microscope: common
measurement is a micrometer (µm) electron microscope: common measurement is a nanometer (nm) |
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What are the metric units mathematical relationships to each other and to a millimeter?
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1 micrometer = 1 thousandth of a millimeter (mm)
or 1 millionth of a meter (m) = 1 x 10-6 m nanometer (nm) = 1 x 10-3µm = 1 x 10-9 m (1 billionth of a meter!) or angstrom (Å) = 1 x 10-1 nm |
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What is the maximum resolving power of the human eye, an "ordinary" light microscope, and a transmission electron microscope?
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human eye: about 0.2mm
light microscope: about 0.2µm transmission electron microscope (TEM) Resolution is approximately 0.1 nm |
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Describe the uses and components of the special stain PAS.
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Periodic Acid Schiff Stain (PAS): Stains carbohydrates, glycogen, proteoglycans,
mucus, basement membrane, cellulose (implanted medical devices); color= magenta. PAS is used to assist in diagnosis of: glycogen storage disease (Gaucher's disease), |
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What is meant by the terms "basophilia" and "acidophilia"?
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hen describing the characteristic staining pattern of an H&E stained slide, we use the
term basophilia (base-loving) to describe components that stain blue with the basic dye (hematoxylin). The terms eosinophilia (eosin-loving) and acidophilia (acid-loving) are used interchangeably to describe components that stain pink with the acidic dye (eosin). |
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Give examples of macromolecules that can be stained by eosin and whether they would appear basophilic or acidophilic.
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described as acidophilia or eosinophilia
Components stained: • most proteins (not all) • cytoplasm • cytoplasmic filaments • secretory vesicles • collagen • elastic fibers |
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Describe the uses and components of the special stain heavy metal.
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Metal stains, such as silver, gold and osmium tetroxide are heavy and thus allow resolution of tiny structures that would otherwise not be
observed in an H&E preparation. Heavy metal stains stain the tissues black. |
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Give examples of macromolecules that can be stained by hematoxylin and whether they would appear basophilic or acidophilic.
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escribed as basophilia
Components stained: • nucleus (heterochromatin and nucleolus) • ribosomes • rough endoplasmic reticulum |
