| dens succedaneus | One of the 32 teeth belonging to the second or permanent dentition; eruption of the permanent teeth begins from the fifth to the seventh year, and is not completed until the seventeenth to the twenty-third year, when the last of the wisdom teeth appears. Synonym: dens permanens, dens succedaneus, second tooth, secondary dentition, succedaneous dentition, succedaneous tooth. (05 Mar 2000) |
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| dense bodies | <cell biology> Areas of electron density associated with the thin filaments in smooth muscle cells. Some are associated with the plasma membrane, others are cytoplasmic. (12 Jan 1998) |
| dense liver | <radiology> Haemochromatosis, haemosiderosis, Wilson disease, Thorotrast, amiodarone, gold (for RA) (12 Dec 1998) |
| dense metaphyseal bands | <radiology> Normal variant, stress lines, heavy metal poisoning, treated rickets, scurvy, hypervitaminosis D (12 Dec 1998) |
| dense spleen | <radiology> Sickle cell disease, haemochromatosis, Thorotrast (12 Dec 1998) |
| dense-deposit disease | See: membranoproliferative glomerulonephritis. (05 Mar 2000) |
| densification | A mechanical process to compress biomass (usually wood waste) into pellets, briquettes, cubes, or densified logs. (05 Dec 1998) |
| densimeter | Synonym: densitometer. Origin: L. Densitas, density, + G. Metron, measure (05 Mar 2000) |
| densitometer | 1. An instrument for measuring the density of a fluid. Synonym: densimeter. 2. An instrument for measuring, by virtue of relative turbidity, the growth of bacteria in broth; useful in microbiologic assay of nutrients and antibiotics, phage studies, etc. 3. An instrument for measuring the density of components (e.g., protein fractions) separated by electrophoresis or chromatography, utilizing light absorption or reflection. 4. An electronic instrument for measuring the blackening of radiographic film by X-ray exposure; used for film sensitometry, bone densitometry, measurement of line spread function (microdensitometer). Origin: L. Densitas, density, + G. Metron, measure (05 Mar 2000) |
| densitometry | A procedure utilizing a densitometer. (05 Mar 2000) |
| densitometry, X-ray | Measurement of the degree of darkening of X-ray film by means of a photocell which measures light transmission through the film. (12 Dec 1998) |
| density | 1. <radiology> The amount of darkness or light in an area of a scan reflects the compactness and density of tissue. Differences in tissue density are the basis for CT and MR scans. 2. <microscopy> Logarithm to the base 10 of the reciprocal of transmittance. (12 Jan 1998) |
| density dependent inhibition of growth | <cell culture> The phenomenon exhibited by most normal (anchorage dependent) animal cells in culture that stop dividing once a critical cell density is reached. The critical density is considerably higher for most cells than the density at which a monolayer is formed, for this reason, most cell behaviourists prefer the term density dependent inhibition of growth as this avoids any confusion with contact inhibition of locomotion, a totally different phenomenon that is contact dependent. (12 Jan 1998) |
| density gradient | <chemistry> A column of liquid in which the density varies continually with position, usually as a consequence of variation of concentration of a solute. Such gradients may be established by progressive mixing of solutions of different density as for example: sucrose gradients) or by centrifuge induced redistribution of solute (as for caesium chloride gradients). Density gradients are widely used for centrifugal and gravity induced separations of cells, organelles and macromolecules. The separations may exploit density differences between particles or primarily differences in size, in which latter case the function of the gradient is chiefly to stabilise the liquid column against mixing. (12 Jan 1998) |
| density gradient centrifugation | <technique> High-speed centrifugation inwhich molecules float at a point wheretheir density equals that in a gradient of cesium chloride or sucrose. (12 Jan 1998) |