From:"J. A. Kiernan"

If you know what this solvent is, it should be easy
enough to find it in a chemical supplier's catalogue.
If you don't know what it is, can you justify using
it?  An unknown solvent used in microtechnique might 
have unknown effects - good or bad - on your preparations,
and it might also have unknown toxic or other hazardous 

A clearing agent (whether to precede paraffin or a
mountant) is chosen for its miscibility with other
solvents, its chemical unreactivity (if that's a word),
its viscosity, and its refractive index. Low toxicity
and (for most of us) low price are also important.
If you know your need, there's a simple solvent that
will meet it. In practical terms, half a dozen
such solvents should satisfy almost every demand for
a "special" clearing agent. 

There are "preferred" clearing agents for particular
purposes, such as cedarwood oil when mitochondria are
to be stained with dyes, creosote of beechwood 
for some old neurological stains, and methyl salicylate
for stained whole amphibian and chick embryos. These
preferences are based on physical properties such as
high viscosity (cedarwood oil persists in the wax
block and facilitates cutting thin sections) and
refractive index (meth sal is not quite glass-like;
benzyl benzoate is better but it doesn't have a nice
wintergreen odour; methyl benzoate is better still
for refraction, but it stinks). Sorry for that
awfully long sentence!
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1

> "Still, Lee-Ann" wrote:
> Hi Histonetters,
> I'm looking for the agents or the company that makes
> Micro-Clear Tissue Clearing Agent, either in the USA or down
> under in Australia or New Zealand.
> Would be most grateful if you could E-Mail me the details.
> Thanks in anticipation.
> Lee-Ann Still   Reproduction Group
> AgResearch Wallaceville Research Centre
> P.O. Box 40063, Upper Hutt, New Zealand

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