[Histonet] Polymer Paraffin

[John Kiernan]

Dear Igor  Deyneko,

Go for simple paraffin wax that melts between 55C and 60C. Additives, especially unidentified polymers, probably have little value. Read on, and check the Web and Library references.

The various paraffins and additives were discussed on Histonet several (8-10) years ago, and the replies included comments from the major authority in this field, Russ Allison of the University of Wales Dental School in Cardiff.  I hope this information is still available by way of Histosearch.com, because Russ's original publications in the field are not in many libraries outside Britain and the Commonwealth. 
 
Russ Allison is one of the authors of the 4th (last, 1985) edition of C.Culling's excellent textbook, and he published significant original papers on waxes from the mid-1970s up to 1998. He compared many commercial and extempore formulations (more than a hundred, if I remember rightly) using physical measurements of the variation in force resisting the passage of the block face across the blade, scanning EM to see how solidification of the wax deformed fine structure, and determination of the rate of infiltration of tissue, and how this was affected by temperature, MW of the wax, additives etc. His bottom lines were that:\

1. Additives  to paraffin, declared or secret, have no effect on cutting or the appearance of stained sections. This conclusion dismissed many unprovedc claims for additives to paraffin wax. The secret polymer additives (often with  short lifespans, according to the salesmen) do not help in any way.

2. Infiltration by paraffin is somewhat quicker if the wax contains some DMSO (= dimethyl sulphoxide, a solvent miscible with nearly everything).  

All but the most recent of Russ Allison's papers were published in a British journal that has changed its name too many times. Some are in the British Journal of Medical Laboratory Science, and others are in Medical Laboratory Sciences.  The volume numbers are continuous, dating from the good old  Journal of Medical Laboratory Technology, which contains some real classics  in the field of Histotechnology.

John A. Kiernan
Anatomy & Cell Biology
University of Western Ontario
London, Canada  N6A 5C1
------
Igor Deyneko <igor.deyneko <@t> gmail.com> wrote:
>  Dear Histonetters! I was just wondering, can someone 
> advise a good
> embedding
> paraffin for me? I embed tumors mostly, and occasional livers 
> and pancreas,
> and very rarely colon. The 1 I'm using right now, Richard-Allen 
> #6, I'm not
> crazy about. I am looking for one preferably with polymers. Has 
> anyone ever
> used the SurgiPath Embedding paraffin and what are your reflections?
> Thank you.
> Igor Deyneko.
> Infinity Pharmaceuticals
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