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In microscopy, negative staining is an established method, often used in diagnostic microscopy, for contrasting a thin specimen with an optically opaque fluid. In this technique, the background is stained, leaving the actual specimen untouched, and thus visible. This contrasts with positive staining, in which the actual specimen is stained.
Negative staining Adsorption onto tissue or the surface of viruses and its electron density are the bases of phosphotungstic acids action as a negative stain. This electron density arises from the presence of the 12 tungsten atoms which each have an atomic number of 74. The mechanism of the adsorption onto tissue has been proposed as being ...
The negatively charged cell wall of many microorganisms attracts the positively charged chromophore which causes the specimen to absorb the stain giving it the color of the stain being used. Positive staining is more commonly used than negative staining in microbiology. The different types of positive staining are listed below. [1]
Sucrose is the only sugar that bacteria can use to form this sticky polysaccharide. [1] However, other sugars—glucose, fructose, lactose—can also be digested by S. mutans, but they produce lactic acid as an end product. The combination of plaque and acid leads to dental decay. [12]
DAPI can be used for fixed cell staining. The concentration of DAPI needed for live cell staining is generally very high; it is rarely used for live cells. [ 7 ] It is labeled non-toxic in its MSDS [ 8 ] and though it was not shown to have mutagenicity to E. coli , [ 9 ] it is labelled as a known mutagen in manufacturer information. [ 2 ]
Gram stain (Gram staining or Gram's method), is a method of staining used to classify bacterial species into two large groups: gram-positive bacteria and gram-negative bacteria. It may also be used to diagnose a fungal infection. [1] The name comes from the Danish bacteriologist Hans Christian Gram, who developed the technique in 1884. [2] Gram ...
Failure to completely clean out the necrotic soft tissue of the pulp system may cause staining, and certain root canal materials (e.g., gutta percha and root canal sealer cements) can also. [1] Another possible factor is the lack of pulp pressure in dentinal tubules once the pulp is removed, leading to incorporation of dietary stains in dentin. [1]
Rubber cups, also called prophy cups, are used in the hand-piece. Polishing paste, prophylactic paste, usually containing fluoride, is used with the rubber cups for polishing. Rubber cups should not be used over the cementum area as it may remove a layer of cementum at the cervical area. There are two popular types of prophy cups: 4 webs and 6 ...