Debbie,

My understanding is that yellow birefringence is a result of a combination
of one or more of 3 factors;  (i)  Sections too thick
			      (ii)  Orientation of amyloid fibrils
			     (iii)  Quality of optics in use

Regards

Ken.

At 09:41 AM 1/13/00 -0600, you wrote:
>  Hi everyone,
>I would like to ask if anyone knows why amyloid on Congo Red stain would
>birefringe as a orange-yellow color instead of apple green?  We are using
>the same procedure that we have used for years.  Our procedure is a Puchtler
>Modification.  If anyone has any ideas, I would appreciate hearing from you.
>Thanks in advance.
>
>Debbie J. Siena, HT(ASCP)QIHC
>Histopathology Manager
>Baylor University Medical Center
>Dallas, TX 75246
>214-820-2465
>
>
Kenneth W Turner
Senior Teaching Fellow
Manager Histology Service Unit
Department of Pathology
Dunedin School of Medicine	    e-mail  ken.turner@stonebow.otago.ac.nz

University of Otago		    Phone:  (03) 479 7135 or (03) 479-7152
New Zealand			    Fax:    (03) 479-7136