Are the polarization colors of picrosirius red-stained collagen determined only by the diameter of the fibers?

Histochemistry. 1989;93(1):27-9. doi: 10.1007/BF00266843.


Polarization colors of various purified collagens were studied in fibers of similar thickness. Three different soluble collagens of type I, insoluble collagen type I, lathyritic collagen type I, two p-N-collagens type I, pepsin extract collagen type II, two soluble collagens type III, p-N-collagen type III, and soluble collagen type V were submitted to a routine histopathologic procedure of fixation, preparation of 5-microns-thick sections, staining with Picrosirius red and examination under crossed polars. Polarization colors were determined for thin fibers (0.8 micron or less) an thick fibers, (1.6-2.4 microns). Most thin fibers of collagens and p-N-collagens showed green to yellowish-green polarization colors with no marked differences between the various samples. Thick fibers of all p-N-collagens, lathyritic and normal 0.15 M NaCl-soluble collagens showed green to greenish-yellow polarization colors, while in all other collagens, polarization colors of longer wavelengths (from yellowish-orange to red) were observed. These data suggested that fiber thickness was not the only factor involved in determining the polarization colors of Picrosirius red-stained collagens. Tightly packed and presumably, better aligned collagen molecules showed polarization colors of longer wavelengths. Thus, packing of collagen molecules and not only fiber thickness plays a role in the pattern of polarization colors of Picrosirius red-stained collagens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Azo Compounds
  • Cattle
  • Collagen / analysis*
  • Collagen / classification
  • Color
  • Coloring Agents*
  • Humans
  • Microscopy, Polarization
  • Picrates
  • Rats
  • Staining and Labeling*


  • Azo Compounds
  • Coloring Agents
  • Picrates
  • C.I. direct red 80
  • Collagen