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Special Stains - Picrosirius Red

  • Picro-Sirius red Trichrome background
  • Special staining Technique

The polyazo dye sirius redF3B has much larger molecules than acid fuchsin and it is also able to assume a planar configuration. A solution in picric acid provides red staining of collagen and a yellow background. In ordinary light, the sections closely resemble those stained by van Gieson?s method. Picro-sirius red is used mainly in conjunction with polarised light microscopy: the natural birefringence of collagen is greatly enhanced by the binding of long, aligned molecules of sirius red. When examined through crossed polars, collagen fibres stand out brilliantly against a dark background.


1.    Take sections to water.

2.     Stain in picro-sirius red solution for one hour

3.     Wash in two changes of acidified water.

4.     Dehydrate in three changes of 100% alcohol.

5.     Clear and mount


Light Microscopy

Collagen -                                 Red

Cytoplasm-               Yellow

Polarising Microscopy

Large Collagen Fibres Yellow or orange birefringence

Thin Collagen Fibres Green birefringence

Photo - x10 Picrosirius Red

picro Sirius red on liver