Re: paraffin survey


I've been a pathologist since - gack - 1964 - and, while there've been many 
ups and downs, in general the slides are a great deal better than they were 
when I was a resident. I have the abiding suspicion that improved embedding 
media are the biggest single reason for this improvement.

In 1964 tissue was embedded in paraffin - a complex and ill defined mixture 
of natural aliphatic hydrocarbons (the word "paraffin" is a blend of two 
Latin words "parum affinis" literally meaning 'little related' - doesn't 
combine with anything). You could actually go to the grocery store and buy 
the wax that home canners used, and some labs did this.

Today's embedding media are complex mixtures of organic molecules that may 
have been mentioned in my 1957 organic chemistry course some spring day when 
I cut class to drink beer on the banks of the Charles. Their composition is 
entirely trade secret, and even if it were revealed it wouldn't tell most of 
it very much. This evolution occurred with little if any documentation in the 
literature - for example, a review of embedding media in the J Histotechnol a 
few years ago barely mentioned it.

What happened? I've always wondered.

Bob Richmond
Samurai Pathologist
Knoxville TN

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