Re: sectioning insects

From:Gordon Couger

All you need is a prescription from a vet or doctor and take it to a
compounding pharmacy if you want it in something other than the standard
dosage for medication. It is still used in human medicine as well. It is not
a controlled narcotic so there is very little hassle.


Gordon Couger
Stillwater, OK

From: "Tom Clarke" 

: Hi Barry,
:   Thanks for the reply.  I can probably get my hands on chloral hydrate as
: have a vet school on campus and I think that drug is still used as an
: anesthetic, though I suspect it will be a red-tape hassle.  Do you know if
: the chloral hydrate is  necessary, (ie., can treating with phenol have the
: same effect?) or if another chemical can substitute it?  The specimens I'm
: working on are late instar caterpillars, so the cuticle isn't overly tough
: but still sufficently strong to cause problems in sectioning.
:   -Tom Clarke-
: Barry Rittman wrote:
: > Tom
: > Most of the experience I had sectioning insects was looking at
: > dragonflies and dragonfly larvae almost 40 years ago but I did spend a
: > lot of time researching of methods to produce sections of the head
: > regions.
: > The most effective method I found was to concentrate on the processing
: > itself. I mixed melt equal parts of chloral hydrate and phenol together
: > by gentle warming and used as the chitin softening agent (I cannot claim
: > credit for this and chloral hydrate is probably difficult to get chloral
: > hydrate unless in business of shanghaiing sailors!)). This solution was
: > used after dehydration and specimens were left for up to a week in this
: > solution. Usually a day was adequate but did not hurt leaving much
: > longer. Then chloroform as an intermediary agent.
: > Most of the other methods that I tried such as softening with hydroxides
: > did not seem to be effective.
: > I think that effectiveness may depend largely on the insects and
: > will not work with thick shelled coleoptera.
: > Some of the older methods suggested snipping off a piece of the outer
: > chitin to allow penetration of agents through the rest of the body of
: > insects.
: > An alternate is to use double embedding with celloidin-wax. Found this
: > work but not as well as first method.
: > Yet another method was to use isopropyl alcohol dehydration in place of
: > ethanol dehydration to minimize hardening. Worked reasonably well for
: > larvae but was not as effective for  adult dragonflies.
: > If the insects have already been embedded I would recommend soaking the
: > block in water or using Mollifex.
: > If the chitin tends to separate you might try to use the technique of
: > wiping a block of 45 degree wax over the surface before cutting each
: > section. Failing this (and probably by this time after several
: > Guinesses)- try  painting a thin layer of celloidin on the surface,
: > to dry and then cut the sections. This is time consuming but sometimes
: > works.
: > Effects on DNA - no idea?
: > Barry
: >
: > Tom Clarke wrote:
: >
: > > Does anyone have any experience sectioning paraffin embedded insects?
: > > Are there any methods that can be used to soften the chitin without
: > > significantly damaging the other tissues (in particular, the DNA)?
: > >
: > >   -Tom Clarke-
: > >    Division of Biology
: > >    Kansas State University

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