Decalcification
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| Removal of calcium salts from bone or calcified tissues | Decalcification
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| _____ tissue w/large amounts of calcium results in torn/ragged sections and damage to the cutting edge of microtome | Failure to decalcify
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| for routine dx purposes use formalin, use it unbuffered since calcuim phosphate present in the bone serves as an adequate buffer to keep the pH above 6.0, | Fixation
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| Nucleic acids are suscpetible to ribonuclease digestion or digestion by mineral acids,if formalin fixation is prolonged more than two days | Nucleic acids
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| acid methods (acid, ion exchange, electrolytic method) chelating method | Two Routine decalcification methods
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| The stronger the acidity of solution,the longer the specimen remains in it, the more subsequent staining will demonstrate injurious effects of the decalcification. most pronounce effect-nuclear bsophilia | Acid method
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| may result in a total lack of nuclear staining | over decalcification
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| calcium salts dissolve and then ionize. | principle of acid method
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| soluble at a pH of 4.5 | calcium salts
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| pH between 0.5-3.0 | decal solutions
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| used in concentration of 5%-10% | simple acids
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| decalcify fairly rapidly | hydrochloric and nitric acids
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| can cause serious deterioration of tissue beyond 48 hours | Nitric acid
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| slower acting, can remain in solution for two weeks | Formic acid
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| great for simultaneous fixation and decal | formic acid and formaldehyde
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| should be suspended in an embedding bag to expose all the surfaces of the specimen | specimen
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| at the initial stage aids in infiltrating the specimen w/decal solution and will draw off carbon dioxide bubbles that form on the specimen surface | Vacuum
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| migrate out of the tissue into the surrounding solution. solutions around the tissue may become saturated, so the solution should be changed frequently | calcium ions
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| change frequently | solution
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| never use _____to speed up decal process. | heat
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| it increases the effects of decalcifying fluids on other tissue components, swelling and maceration will most likely occur | heat
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| involves use of formic acid over a layer of an ammoniated salt of a sulfonated resin | Ion exchange resins
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| exchanged for calcium ions, this keeps solution free of calcium ions and speeds up the reaction. solution doesnt need to be changed frequently | ammonium ions
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| the best decal method | ion exchange resins
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| utilizes a mixture of formic and hydrochloric acid placed in an apparatus based on a simple ectroplating device | electrolytic method
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| The bone is attached to the anode (+) and a current is passed through the solution. The calcium ions (+ charge) are attracted to the cathode (-). | electrolytic method
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| decal process takes 2-6hours, one sample per day can be processed. | electrolytic method
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| heat generated by this method has a potential for tissue destruction, a total loss of cellular detail and stainability | electrolytic method
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| organic compounds that have the property of binding certain metals | chelating agents
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| ethylenediaminetetraacedic acid | EDTA
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| solution should be between 5.0-7.2 | Chelating agents
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| Binds calcium ions | EDTA
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| Very slow method but many enzyme methods can be used | chelating agents
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| sectioning is difficult | underdecalcification of tissue
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| stain is very poor | overdecalcified tissue
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| three basic method - mechanical/physical, chemical, radiographic | end of decalcification
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| testing flexibility of specimen, probing the specimen with needle or pin, | Mechanical method
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| least desirable method, it is inaccurate and can create artifacts | mechanical method
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| depends on the precipitation of calcium oxalate | Chemical method
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| mixing a sample of the used decal solution w/a solution of ammonium hydroxide and ammonium oxalate. if solution remains turbid it indicates the presence of calcium | Chemical method
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| keep retesting decal solution until free of calcium | Chemical method
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| Yields a visual evidence that demineralization is complete. most accurate method. | Radiography
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| Do not use on metallic fixed tissue such as Zenker or B-5 solution. metal will render the specimen radiopaque | Radiography
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| wash tissue w/running wather or lithium carbonate to neutralize any remaining acid, then routinely process the specimen | after decalcification
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| Glycol methacrylate is the most frequently used embedding media. | undecalcified bone
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| section of bone may be ground with waterproof sandpaper to a thick of 75-100 microns. these ground sections may be stained and mounted on glass slides | undecalcified bone
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| alcohol, buffered formalin or calcium formalin | fixatives of choice
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| interefere with most techniques | metallic fixatives
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| examined for diagnosis of metallic bone disease | undecalcified bone
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| neutralizes remaining acid before processing the specimen | lithium carbonate
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Created by:
nperez
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