Metachromatic (from the Greek. meta - through and chroma - color, color) - changes the color of water solutions of some of the main colors (toluidine-blue, azure And, methylene blue, tinin and so on) in the presence chromotropic substances. Chromotrope that metachromatic, can be of different chemical nature, but in biological objects is often mucopolysaccharides (hyaluronic and hondroitina acid, heparin, keratolytic and others), and nucleic acids.
The mechanism of metachromatic clear enough. Believe polymer properties of the substrate, which is connected dye, induce polymerization past that leads to metachromatic. Assume also that metachromatic due to the formation of fragile adsorption connection cation paint with hronotroponam polyanion. This assumption explains the dependence M from the concentration of chromotrope and ionic strength of the solution, and also agrees well with the data histochemical studies.
In histochemistry Meters are widely used for detection of acid mucopolysaccharides and nucleic acids research fibrinoid, amyloid substance, etc. is used in combination with metachromatic staining set of enzymes (hyaluronidase, lidaza, amylase, and so on), specifically gidroliznaya substrate, we can identify a number of proteins in the tissues.