Metachromasia


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metachromasia

[‚med‚ə·krō′mā·zhə]
(chemistry)
The property exhibited by certain pure dyestuffs, chiefly basic dyes, of coloring certain tissue elements in a different color, usually of a shorter wavelength absorption maximum, than most other tissue elements.
The assumption of different colors or shades by different substances when stained by the same dye. Also known as metachromatism.

Metachromasia

 

in biology, the property of cells and tissues that causes them to take on a color that differs from that of a dye. For example, in staining with thiazine dyes, the basic matter of connective tissue, tumor cells, and certain other cells are stained not blue or violet, the color of the dye, but red or pink. It is thought that metachromasia is caused by the polymerization of the dye molecules under the influence of free negative charges in the tissue.

References in periodicals archive ?
Caption: Figure 7: Toluidine blue staining showing typical metachromasia of cartilage.
muscoides SPs physical and chemical characterization by agarose gel when Am-1 did not appear on gel and Am-3 had an intense metachromasia, as well as differing from other studied algae species SPs (Athukorala et al., 2006; Rodrigues et al., 2009; Rodrigues et al., 2011; Araujo et al., 2012).Thus, it was speculated that this algal species would perhaps biochemically change its matrix polysaccharide composition according to the collection period (Zvyagintseva et al., 2003; Cardozo et al., 2007; Pereira & Costa-Lotufo, 2012).
According to the histological section prepared from the pellet at day 21 of culture, the amount of metachromasia seemed to be higher in cultures with 0.01 and 0.05 [micro]M BIO compared to that of the control and cultures with 0.1 and 1 [micro]M BIO.
This result found also that the cytoplasm and nuclei of the vaginal epithelium undergo metachromasia, through which the tissue colour shifts from blue to red or purple.
Mast cells in this connective tissue layer were most noticeable in Toluidine blue sections as the cytoplasmic granules took on a purple colour due to metachromasia (Figures 3(a) and 4(a)).
They were evaluated by the content of hexuronic acid (carbazole reaction) and the metachromasia produced by the glycosaminoglycans sulfated in the presence of 1.9-dimethylmethylene blue (FARNDALE et al., 1986).
Because of their high content of acidic radicals in their sulfated glycosaminoglycans, chondrocyte granules displayed metachromasia. Sections showed the strong staining of metachromatic territorial matrix-surrounded cells and they changed the color of toluidine blue to purple/ red (Figures 7C and 7D).
On histologic examination, granules exhibited a typical, although faint, metachromasia with toluidine blue and Giemsa stains (Fig 2D).
Metachromasia in the dye polymer interaction has been studied extensively since the discovery of this phenomenon in 1875 [1].
At 1 and 30 days after the treatment a significant increase of metachromasia was observed at doses of 150 and 600 mg of malathion.