Re: [Histonet] Grocott's Methenamine Silver Stain

From:Kathleen Roberts

OK, so I guess I'll get some solid chromium trioxide and make it up that 
way and see if it makes any difference, though if the samples are 
over-oxidized, I may not be able to get anywhere with least 
I'll be able to work it out with the control slides.

Thanks for the reminder about reminded me that, since I 
am the chemical safety officer for the lab, that I need to get a list 
together of all the stuff that Rutgers Env. Health & Safety needs to 
pick up and send it over to them.  My to-do list never ends...  :o)

Thank you very much for your help-

Gayle Callis wrote:

>Dissolve 4 gms chromium trioxide in 100 mls of distilled water, a simple
>chemical solution. Chromic acid is a misnomer from years ago, it is made
>from chromium trioxide. I have used 5% but 4% is the norm.  I do use a
>solution for 1 week if I am still doing the stain the next day. 
>Remember you CANNOT dump chromium solutions down the drain, toxic waste and
>must be collected. 
>By the way, lithium carbonate will only neutralize any residual acid left
>in tissue which damages nuclei by acid hydrolysis of DNA/RNA, and may help
>restore the staining of hematoxyling.  Howeer, LiCO3, a base, does NOT
>reverse the chemical effects of acid IF you have overoxidized the groups
>you want to bind silver to with GMS.  Once protein hydrolysis is done and
>gone beyond the endpoint you need, you are in trouble. 
>This is the reason that hydrochloric acid and even formic acid is not
>advised IF you want to do a Feulgens staining reaction for DNA, the
>hydrolyzation step is basically overdone, and you get weak to no staining.    
>Gayle Callis
>Research Histopathology Supervisor
>Veterinary Molecular Biology 
>Montana State University - Bozeman
>PO Box 173610
>Bozeman MT 59717-3610
>406 994-6367 (lab with voice mail)
>406 994-4303 (FAX)

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