Re: FW: brain section blowout
|From:||"Anthony f. Brandwood" <firstname.lastname@example.org>|
--On 28 May 2001 10:39 -0400 "J. A. Kiernan" <email@example.com> wrote:
> On Fri, 25 May 2001, Stephanie Rodriguez wrote:
>> Date: Fri, 25 May 2001 08:13:15 -0700
>> When I float my ribbons out on my water bath, the sections rapidly come
>> apart before I have a chance to get them on a slide.
>> Could it be that the tissue is not adequately fixed? or perhaps poorly
> It has to be one or the other or both. For reasons given below
> I think your difficulties are due to improper processing after
>> I fixed the whole mouse brains in 10% NBF for 8hrs at RT, then
>> 72hrs at 4C, then sent them to the contract lab ...
> The 3 days at 4C is a bit strange. If you want minimal formaldehyde
> fixation, why not move the specimens into 70% alcohol after a few
> hrs (and thereby obtain mostly alcohol fixation)? If you want real
> formaldehyde fixation, why do it in a cold place that can only slow
> down the chemical reactions?
> Formaldehyde isn't a _very_ good fixative when you want paraffin
> sections, but it is _fairly_ good, and it's also routinely used
> by nearly everyone, so its bad effects (differential shrinkage,
> weary-looking nuclei etc) are so widely recognized that they
> are passed off as "normal."
> Fragmentation of paraffin-embedded tissue when floated on a
> warm water bath is _not_ one of the faults of formaldehyde or
> any other fixative. Your problem has to be the fault of the
> contract lab that collects money for not dehydrating, clearing,
> infiltrating and properly blocking out your specimens.
> John A. Kiernan
> Department of Anatomy & Cell Biology
> The University of Western Ontario
> London, Canada N6A 5C1
We have also had this problem occuring from time to time with formalin
fixation but it has always happened to one or two blocks of CNS tissue
which have been processed with other CNS blocks and these have cut without
any problem at all. The blocks had not been jammed tight in the basket
during processing and all the solvents had been reasonably fresh and the
processing schedule been used for many years to process CNS tissue without
many problems. Any Suggestions?
Department of Veterinary Pathology,
University of Liverpool,
Tel. No. 0151-794 4251
Fax. No. 0151-794 4268
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