LEROY BROWN wrote:

> A friend has asked the following question,  anyone know what to advise on
> the question?
>
>  I was wondering if you might help me answer a relatively simple question
>  on histology technique.  I've got a protocol that is for staining and
>  dehydrating nissl sections for brain tissue.  It goes through several
>  steps, starting by dehydrating and then soaking in 50/50 CHCl4/100%EtOH,
>  then hydrating to stain, then clearing, and dehydrating and finally
>  soaking in xylene before coverslipping.
>
> What are the purposes of using  chloroform and xylene in clearing/staining
> tissues?  Do they serve  different purposes?  Do you know what they actually
> do to the tissue, chemically?  Any help you could give me would be wonderful
> and  informative.

    For frozen sections, some like to 'defat' (remove myelin) from the sections
before Nissl staining. Some Nissl stains will stain myelin or precipitate on it.

    I often use Toluidine Blue or Thionin as a light Nissl counterstain for
immunos showing glia, if I dehydrate with actone I get a slight metachromatic
staining of myelin which I find attractive.
    Your mileage may vary.

Geoff
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Geoff McAuliffe, Ph.D.
Neuroscience and Cell Biology
Robert Wood Johnson Medical School
675 Hoes Lane, Piscataway, NJ 08854
voice: (732)-235-4583; fax: -4029
mcauliff@umdnj.edu
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