Re: MSB Trichrome stain.
|From:||"J. A. Kiernan" <firstname.lastname@example.org>|
On Sat, 23 Sep 2000 Jakrobsmith@aol.com wrote:
> Does anyone else out there in histoland not put PTA in their martius yellow?
> Any comments would be appreciated.
It doesn't make sense to do so, in terms of the conventional wisdom of
trichrome staining or the various less conventional theories. If your
observation is really true, it may mean that the older ideas are wrong,
and we need to re-think the way these stains work.
The obvious First Test is to find out if the effect of adding PTA to
the martius yellow solution changes anything other than the pH. Check
the pH of your martius yellow with & without PTA (which will acidify
the solution). Use hydrochloric or sulphuric acid to make a solution
with the same pH, and see if all that phosphorus and tungsten really
makes any difference. Lillie did experiments of this kind, and was
not impressed with the notion of PMA and PTA as "colourless acid dyes"
promoted by J.R.Baker. I think most other investigators would
disagree with Lillie on this one.
PTA (or PMA) attaches to collagen and displaces medium-size dye
anions (usually red) from it, but doesn't do the same for
cells (except for certain secretory granules). For reasons that
aren't glaringly obvious, PTA allows the largest dye anions of
the trichrome mixture (usually aniline blue or fast green FCF)
to bind fairly selectively to collagen. The smallest dye
anions (orange or yellow) ideally localize only in red
blood cells and certain secretory granules. Quite a good
argument can be made for the case that these objects are
too densely textured to admit and retain dye ions of
different sizes, so they preferentially retain the smaller
John A. Kiernan,
Department of Anatomy & Cell Biology,
The University of Western Ontario,
LONDON, Canada N6A 5C1
Phone: (519) 661-2111
FAX (Department): (519) 661-3936
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