That's what I thought was happening, in terms of the aldehydes. Similar to
the Feulgen stain.

However, the tissue looked "funny", like some of the cytoplasm was
missing, so I wondered if acid could "leech" out glycogen, like it could
with iron or calcium. It wasn't my first thought, but after 40 minutes in
two changes of Schiff with TOO high a concentration of HCl, I was
just wondering if leeching was also a possibility.

Thanks to Gayle and Joseph for replying.

Peggy Wenk, HTL(ASCP)
William Beaumont Hospital
Royal Oak, MI 48073

----- Original Message -----
From: "Gayle Callis" <uvsgc@montana.edu>
To: "Lee & Peggy Wenk" <lpwenk@mail.netquest.com>
Sent: Tuesday, May 01, 2001 1:17 PM
Subject: Re: PAS CHEMISTRY QUESTION


> Pure chemistry Peggy, the concentrated HCl hydrolyzed the vicinal OH
groups
> past the usable CHO or aldehyde on the glycogen, or overhydrolyzation by
> acid. and if there are no aldehyde groups available, no staining.  Remake
> the Schiffs and make sure it is 1N HCl! So it is the more concentrated
acid
> in the Schiffs that created the problem on the glyogen in tissue, bet my
> bottom dollar!
>
> Also, Culling taught us, in a lecture, to make up periodic acid fresh each
> time, it was also critical the initial oxidation is correct, and that this
> solution is not as stable as we are led to believe. However, that was not
> your problem.
>
>
> At 06:54 AM 5/1/01 -0400, you wrote:
> >Yesterday, one of my students did a PAS and PAS digestion. NOTHING in the
> >glycogen control (liver loaded with glycogen) stained PAS +, including
the
> >reticulin and connective tissue.
> >
> >I did the quality of Schiff reagent test but adding some formaldehyde to
> >some Schiff, and it turned dark purple immediately. So my original
thought
> >was that her new Schiff was OK.
> >
> >So I had her make up some new periodic acid, as the solution she made up
was
> >the last of a bottle, so I thought that might be the problem. So we made
up
> >new periodic acid, put the same slides in the new periodic acid, then
back
> >in her new Schiffs, and still nothing worked.
> >
> >After much digging around, I found out that the student had made the
Schiff
> >with conc. HCl, not 1 N HCl.
> >
> >So, I'm curious. What DID she make? Why DIDN'T it stain anything?
> >
> >We then went and borrowed some Schiff from another lab, and restained the
> >same tissues. The stain worked, but was much lighter in color than usual.
> >Would that much extra HCl remove glycogen?
> >
> >Just my curiosity at work. Thanks for any input.
> >
> >Peggy A. Wenk, HTL(ASCP)
> >William Beaumont Hospital
> >Royal Oak, MI 48073
> >
> >
> >
> >
> Gayle Callis
> Histopathology Supervisor
> Veterinary Molecular Biology
> Montana State University - Bozeman
> Bozeman MT 59717-3610
>
> 406 994-6367
> 404 994-4303 (FAX)
>
>