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23 Cards in this Set
- Front
- Back
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Sampling
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get a representative specimen
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Fixation
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Preserve cell as close as possible to living state/hardens the tissue
examples that coagulate cytoplasm 1. simple - formaldehyde (10 %) 2. complex - Bouin's fluid, Zenkers |
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Dehydration
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to remove water from the sample to allow paraffin impregnation
examples: -gradually increasing conc. of alcohol |
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Clearing
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To take alcohol out and allow paraffin to impregnate the tissue
Examples: -xylol (xylene), toluol, and benzene |
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Infiltrating
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To incrust the sample with paraffin for easy cutting
ex. warm paraffin and then frozen and framed |
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Sectioning
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to cut the sample in slices thin enough with microtome between 3-10 micrometers
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Staining
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to add color for differentiation
hematoxylin and eosin (H&E) most common but not special |
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Mounting
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last step; protects in final medium to observe under microscope
examples: -DPX, canada balsam, xylol |
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Freeze drying method
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to quickly prepare glass slide for rapid study during surgery: freeze, dehydrate, and embed
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Electron Microscopy
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Aim:
-double fixation -quick hydration and clearing -embedding in plastic resins Epon or Araldite -cut with ultramicrotome (glass or diamond knives) 30-50 nm thick -mounting on copper grids -stain with heavy metals agents: -glutaraldehyde for proteins and osmium tetroxide for lipids |
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Eosin-pink stain
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type of dye:
-proteins, membranes, cytoplasm/acid dye |
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Basic dyes-blue stain
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type of dye:
-RNA, DNA, rER, nuclei/basic dye common dye: -hematoxylin |
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Regular stain
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type of dye:
-iron containing cells: muscles, RBCs common dye: -iron hematoxylin |
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What are some of the specific stains?
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Structure - Dye:
Proteoglycans - PAS (Shiff), cresyl violet, toluidine blue, methylene blue Neurons - Nissl, Ag, Osmium, cresyl violet (most common) Elastic Fibers - orcein or resorcein/elastin, Verhoff Reticular - silver stain Blood cells - Romanovsky stains, trichrome Polysaccharides - PAS fibers and cytoskeletal elements - Silver and Gold myelin and lipids - osmic acid |
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Verhoff's stain
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type of dye:
-elastic stain for vascular or respiratory function |
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Romanovsky's stain
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Type of dye:
-blood cells highlighting granules in developing WBCs (giemsa and wright stains) common dye: -toluidine blue |
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Amyloid stain
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amyloid protein deposited in tissue in abnormal condition
identified in alzheimers, parkinsons, and stain is congo red |
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Trichrome stains
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use 3 dyes to highlight RBC in blood vessels or collagen between muscle fibers
examples: Gomori trichrome - green color Masson's trichrome - deep pink nuclei, w/ turquoise collagen |
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Iron-haematoxylin stain
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used in cells containing iron such as RBC/muscle
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Metachromasia
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when structures appear different color than the stain
example: -touidine blue is going to stain mast cells blue and give a purple color |
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lipid stain
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Sudan stain
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Artifacts
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not natural occurrences
caused by a bad histological technique most common cause is poor fixation other examples are: autolysis, poor sampling, shrinkage, folds, dust and defet in knife |
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Special Techniques
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Autoradiography - use of tracer isotopes that are caught by some cells
Immunohistochemistry - fixing antibodies or fixing a dye -cell structures regarded as AG -AB then attaches to AG or cell -Direct - primary AB; Indirect - Secondary against Primary AB (most sensitive) Histochemistry - modification of immunohistochemistry using ABs to identify cell types |
