[Histonet] Picrosirius Red in Valves

[Stephens, Elizabeth Humes]

I'm trying to stain for collagen I in porcine heart valves, but have had trouble getting good staining with various antibodies. Do you know if collagen I can be distinguished from other collagens using picrosirius red with polarized light? I do have a nice Collagen III Antibody (which is the other
major collagen in heart valves), so I could potentially approximate the collagen I as the difference bw picrosirius red and collagen III staining. 

(My problem with collagen I antibodies is that I seem to get strong staining around the collagen dense valve annulus core, but light staining in the areas that stain yellow by Movat. The antibody does bind C-propeptide of collagen I, so I don't know if these precursors would be present around the
annulus core and not within the core?)

Thank you!!