Neuropil is everything that is not composed largely of
cell bodies of neurons or bundles of myelinated axons.
In invertebrates such as insects the neuropil is centrally
located and the neuronal cell bodies are in the outer layers
of the ganglia. A butterfly's "brain" comprises the ganglia
dorsal and ventral to its oesophagus. There is no myelin
(invertebrates never quite got that far) 

If you stain the neuronal cell bodies with a basic dye
(a Nissl stain) the neuropil will be coloured by an acid
dye used as a counterstain. The easiest way to achieve the
desired colour scheme is to use a traditional method for
blood cells such as Giemsa's, Leishman's or Wright's stain.

Every book in this field contains detailed technical 
instructions that havs been heavily peer-reviewed. Your lab
can buy a book for the cost of 25G of a dye or 0.1 ml of a
diluted antiserum. There is no financial reason  for every
hito lab not to have a shelf full of books about histology,
histochemistry and histotechnology. 

If you are seriously into examining neuropil, you will also
need an electron microscope and all the associated equipment
and training. You'll need a bigger investment than asking
questions on the Internet.
-- 
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John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
   kiernan@uwo.ca
   http://publish.uwo.ca/~jkiernan/
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Maria Mejia wrote:
> Greetings! 
> I was wondering if any one is willing to share there protocol for
> viewing
> synaptic neuropils in neural tissue? Is there a tinctorial stain or
> immunohistochemical method that I can use on butterfly brain sections?
> Can anyone please provide alternatives methods for viewing synaptic
> neuropils?
> Any information you can provide will be most appreciated.
> regards
> Maria Mejia
> Smith-Kettlewell Eye Research
> S.F.CA
> email: maria@ski.org
> Lab phone: (415)-345-2185/2165
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