Annica and Michael,

WE have had similar experiences to Annica - there does not seem to be much
of a problem in keeping sections or blocks frozen in the freezer for ages
(although I've never thought of doing it with labelled sections!). The
increasing autofluorescence problem is interesting. It also happen when we
store slides normally in a cool dark place, but it usually take about 6 to
12 months to develop. A few years ago we started using nail polish to seal
our cover slips (to stop them moving around when using oil immersion
objectives on glycerine mounted sections) and the autofluorescence
background no longer seemed to develop. We put it down to the sealing
preventing oxidation (or some other) reaction with the atmosphere. When we
do this, our immunolabelled slides usually last really well for a year or
more with out cold storage. I'd certainly welcome any other comments on
this phenomenon!

IAN



On Thu, 27 Feb 1997 17:33:46 GMT, <[log in to unmask]> wrote:

>Dear Michael Lyon,
>
>I have been doing immunofluorescence since many years and have found that
>fixed, cryostat sectioned, immunoincubated, mounted (in antifading media)
>and viewed or unviewed sections, can be stored for long periods of time if
>kept frozen at -20. Some sections are excellent even after 3
>years!!(Tissues sections of brain, nerves, ganglia, muscle, gut, urinary
>bladder etc.) The autofluorescence gradually increases, however, which in
>some few cases can be good, esp. if colour pictures are taken, when yellow
>autofluorescence contrasts nicely with the apple-gree FITC fluorescence.
>However, with Tex red activation also the yellow autofluorescence shows up
>red.
>
>Sometimes, however, you find that all fluorescence is gone - and we have so
>far not been able to find the reason for this. Different antifading media
>do not seem to be involved. So, look at the sections immediately, to be
>very sure! But, save them in the freezer if you think you can have more use
>for the. If fluorescence is destroyed then, well!
>
>Regards,
>
>Annica Dahlstr=F6m, G=F6teborg, Sweden
Professor Ian Gibbins                         Flinders Microscopy &
Department of Anatomy and Histology            Image Analysis Facility
Flinders University of South Australia
GPO Box 2100 Adelaide 5001                    Centre for Neuroscience
AUSTRALIA
Phone:  +61-8-2045271
FAX:    +61-8-2770085
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