All these methods are sensitive but not specific for amyloid deposits. It's not
the thickness of the section alone that effects vivid colors, also type and kind
of fixative, how long it has been fixed, type of clearing agents and sometime
even the temperature of the paraffin will make a difference.
    I would advice use of c.v., modified congo red and even thioflavin T to
identify amyloid.

Gayle Callis wrote:

> Terry makes a good point particularly on positive control sections.   Some
> histobooks suggest cutting sections for amyloid detection at more than 5 um
> i.e. 10 um.  Could it be due to smaller deposits showing up better with
> thicker sections?
>
> At 03:54 PM 12/17/02 +0000, you wrote:
> >It is a simple fact that small amounts of amyloid will not polarise to the
> extent (vividness) of large amounts. The struggle then is to identify them.
> If they stain with Sirius red are in an appropriate place, and have the
> right appearance, then any amount of light to polarise it is OK with me.
> >
> >In parenthesis, why are the controls for amyloid always from solid amyloid
> spleens etc.? That is to say - loaded.
> >Surely the faintest amount of amyloid is the appropriate control.
> >
> >Terry L Marshall B.A.(Law), M.B.Ch.B., F.R.C.Path
> >Consultant Histopathologist
> >Rotherham General Hospital, Yorkshire
> >terry.marshall@rothgen.nhs.uk
> >
> >-----Original Message-----
> >From: d.segers@planet.nl [mailto:d.segers@planet.nl]
> >Sent: 17 December 2002 15:16
> >To: histonet@pathology.swmed.edu
> >Subject: Analysis of sirius red with polarized light
> >
> >
> >Dear all,
> >
> >In the process of analysis of our picro sirius red stained sections we ran
> >into a discussion on the microscope prefs. We could not come to a conclusion
> >as to how much light must be given. We use 2 polarization filters in crossed
> >position. Some people want to give minimal light in order to prevent
> >overestimation of collagen content, total background is black. Others say to
> >give full light, but than the background becomes somewhat blueish, which
> >cannot be turned to black by adjusting the filters.
> >Does anyone have experience with different lighting on sirius sections? Or
> is
> >anyone aware of literature in which this problem is discussed.
> >
> >Thanks in advance,
> >
> >Dolf Segers
> >Dept. of Experimental Cardiology
> >Thoraxcentre, Erasmus MC Rotterdam
> >The Netherlands
> >
> >
> >
> >
> >
> >
> >
> >
> Gayle Callis
> MT,HT,HTL(ASCP)
> Research Histopathology Supervisor
> Veterinary Molecular Biology - Marsh Lab
> Montana State University - Bozeman
> S. 19th and Lincoln St
> Bozeman MT 59717-3610
>
> 406 994-6367 (lab with voice mail)
> 406 994-4303 (FAX)
>
> email: gcallis@montana.edu