[Histonet] Trichrome Question

[John Kiernan]

Which trichrome method? What kind of section (frozen, paraffin, plastic?)
Any post-fixation in something other than plain formalin before staining? 
Provide the technical details, and you will get lots of advice! 
 
Weeks in formaldehyde is not "prolonged" fixation unless the weeks 
are numerous enough to make years. As a generality, trichrome methods 
do not work very well after fixation in liquids that have formaldehyde as the 
only active ingredient. Postfixation of the sections can compensate. Bouin 
is frequently used. Saturated aqueous picric acid us just as good. There are
published reports that iodine and even citrate buffer will improve trichrome
staining of paraffin sections of formaldehyde-fixed tissue. 
 
"Trichrome" has been applied to several staining techniques that use two 
or more dyes. By convention, since about 1920, trichrome methods have
been those using phosphomolybdic or phosphotungstic acid (or both) to 
enable the staining of collagen and cytoplasm by anionic dyes with sharply 
contrasting colours: blue or green for collagen, and red for cytoplasm
(including smooth & striated muscle). A third anionic dye, typically yellow 
or orange, may be added to stain red blood cells. Instructions for 
trichrome methods can be found in all textbooks of  microtechnique and
histotechnology. 
 
John Kiernan
Anatomy, UWO
London, Canada
= = =
----- Original Message -----
From: angelafogg <@t> aol.com
Date: Friday, November 7, 2008 20:17
Subject: [Histonet] Trichrome Question
To: histonet <@t> lists.utsouthwestern.edu

> 
> Performed a trichrome stain on a piece of colon which had been 
> in formalin for? weeks.? Muscle stained blue instead of 
> red.?What happened?? Does prolonged fixation react this way?
> Hope someone can shed some light on this.
> Regards,
> Angela
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