SELECTIVE STAINING OF COLLAGEN AND ELASTIN BY LUXOL FAST BLUE G IN METHANOL: A HISTOCHEMICAL STUDY

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Abstract
Luxol fast blue G in saturated methanol solution selectively stained collagen and elastin in formalin-fixed tissue sections. This selective staining did not take place when a number of other solvents were used. The possible mechanism of dye affinity for collagen and elastin was investigated. Deamination, acetylation, sulfation, potassium permanganate oxidation, and saponification did not greatly affect staining of collagen, although after deamination, and permanganate oxidation elastin did not stain. Therefore it is unlikely that chemical groups affected by these treatments play a significant role in collagen staining by this dye. Tannic acid treatment of sections prevented their staining by the Luxol-methanol solution. Similar treatment in vitro of collagen and elastin reduced staining but did not completely abolish it. Tannic acid tanning of collagen affects its physical properties by introducing cross linkages, and also interacts with basic protein groups. Nonionic groups are also blocked. Both the physical properties of collagen as a polymer, and its chemical properties may be involved in its affinity for Luxol fast blue G in methanol. Luxol fast blue G is a di- oItolylguanidine salt of a trisazo dye. It is possible that only the molecular arrangement of the dye in methanol is able to complex with collagen. After many of the blockade treatments elastin did not stain. The groups blocked by these treatments must be necessary for binding of the dye by elastin, but not for collagen. The method is simple and would seem adaptable to routine histological use and for studies of the histochemical and staining properties of collagen and elastin.