MASSON'S TRICHROME STAIN, 5 x 250 mL

PRINCIPLE

Trichrome techniques enable the differential staining of collagen, muscle fibres, fibrin and red blood cells. Three different stains are used which selectively stain the different cell structures, nucleus, cytoplasm and collagen fibres. First, the samples are stained with an acid dye, such as Biebrich scarlet. All the acidophilus elements of the tissue (cytoplasm, muscle and collagen) will bind to the acid dye. Then the samples are treated with phosphotungstic and/or phosphomolybdic acid. As cytoplasm is much less permeable than collagen, phosphotungstic and phosphomolybdic acids enable Biebrich scarlet to disseminate from the collagen but not from the cytoplasm. Phosphotungstic and phosphomolybdic acids have numerous acid groups which probably act as a means of binding the discoloured collagen and the aniline blue, which is the collagen stain. The pH of the phosphotungstic/phosphomolybdic solution probably also increases staining, aiding the diff usion of the dye through the collagen.

Trichrome stains make it possible to differentiate between collagen and smooth muscle in tumours, and to identify increases in collagenous tissues in diseases such as cirrhosis of the liver.