[Histonet] Inquiry on Tissue Softening for Microtomy

[Jay Lundgren]

I wouldn't say softening, I would say hydrating.  Ammonia water accelerates
hydration of FFPE blocks.  Nobody knows how it works, it's a mystery.  Or
at least I've never heard a scientific explanation.  Only pseudo-scientific
mumbo jumbo like "facilitates the removal of paraffin" which is false.  Go
soak a solid block of paraffin in pure NH4OH for 24 hours, it won't do
anything.

I was told as a student at AFIP, "It opens the pores of the tissue so water
can get in."  In other words, pseudo-scientific mumbo jumbo.

 It works though.  Somebody needs to get a $150,000,000 NIH grant and do a
research project on how ammonia water hydrates tissue.  I worked with some
lovely Hmong people in California that called it "crying water".

Using it can cause a big interpersonal problem with certain people in the
lab though.  Interestingly, hypersensitivity to smells is one of the
symptoms of autism.  Hypersensitivity to smells is also highly correlated
with bipolar disorder and heightened emotional reactivity.  Sooo...

Jay A. Lundgren, M.S., HTL (ASCP)

On Fri, May 10, 2024 at 11:14 PM John Kiernan via Histonet <
histonet at lists.utsouthwestern.edu> wrote:

>    If you apply the ammonia to the cut surface of the paraffin block, I
> suspect that it softens the tissue in the same way as applying water: by
> entering interstices of the tissue that are not occupied by paraffin
> molecules.
>    I never tried ammonia for this purpose but in the 1960s to early '70s I
> occasionally used a proprietary product called Mollifex, which I see is
> still sold. In 1972 or '73 an elderly technician told me that water was
> just as good, and I soon found out that he was right. Indeed, water had the
> advantage of working in 15-30 minutes rather than taking several hours.
> John Kiernan
> Emeritus, UWO, London, Canada
> https://publish.uwo.ca/~jkiernan/
> = = =
> ________________________________
> From: IGNACIO GONZÁLEZ MASSONI via Histonet <
> histonet at lists.utsouthwestern.edu>
> Sent: May 10, 2024 8:53 PM
> To: histonet at lists.utsouthwestern.edu <histonet at lists.utsouthwestern.edu>
> Subject: [Histonet] Inquiry on Tissue Softening for Microtomy
>
> Dear friends at Histonet,
>
> I hope this message finds you well. I am reaching out to seek your
> expertise on a matter that has piqued my interest in the field of histology.
>
> I am currently delving into the process of preparing FFPE (formalin-fixed,
> paraffin-embedded) tissues for microtomy. Specifically, I am curious about
> the role of ammonia in softening these tissues before sectioning. From my
> understanding, ammonia serves as an alkaline agent that helps neutralize
> formalin's effects and facilitates the removal of paraffin, thus aiding in
> the softening of the tissue.
>
> However, I would greatly appreciate if you could provide a more detailed
> explanation of the chemical interactions at play here. How exactly does
> ammonia interact with the tissue components to achieve the desired
> softening effect? Moreover, are there any best practices or safety
> precautions that one should be aware of when using ammonia in this context?
>
> Your insights on this topic would be invaluable to me and would greatly
> enhance my understanding of the intricacies involved in histological
> preparations.
>
> Thank you for your time and assistance.
>
> Warm regards from Santiago of Chile
>
> Ignacio, Medical Technologist
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