[Histonet] Re:sectioning problems
First and foremost, if you are having the ribbon pulling up as chuck with
block (Point #3) you need to make sure knife angle setting on the
microtome is correct. Check your manufacturers instructions on HOW to set
a correct knife angle for your particular microtome. it sound as though
the clearance angle is incorrect. I don't think the paraffin is the
problem, see last comments.
You did not say what tissues you are sectioning animal? human? mouse? nor
how the tissue is processed? If the tissues are dehydrated, cleared and
infiltrated with paraffin - optimally for your particular tissue? then you
should experience good sectioning with correct microtome settings. Beware
of infiltrating tissues with excessively hot paraffin, 60C is all that we
allow with all your animal tisues, over that - I think and with long
infiltration times, you dry out and create some sectioning problems.
64C is pretty hot in my estimation for embedding, with ANY paraffin. We
set ours at 60C only. You have hot and cold surfaces on your embedding
center to help you out, these are usually preset at factory although we can
change that with our Sakura embedding center. Too hot is an enemy, as you
cook the tissues even more. Even the kind of blades you use will affect
how your sectioning goes, and we all have our favorites - be sure to try
others on the market!!!
Dirrerent brand paraffins will have different sectioning qualities
depending on what additives they add to make sectioning easier, etc. Some
paraffins are sticky, others are harder, some you have more compression,
but with care and correct knife angle setting, one can usually learn to
work with ANY paraffin. These additives will cause the paraffins to look
different too - opacity, clarity, hardness, ribboning ability, tackiness as
you have noticed.
Although I like flowers, I favor the brownies!!!
At 11:20 PM 9/22/2005, you wrote:
>I recently have been having problems pulling ribbons from my microtome and
>wondering if anyone has advice.
>1.) I was having problems pulling ribbons from newly embeded blocks, but
>ones that had
>been embeded previously were very easy to pull ribbons from. The new ones
>curl on the blade and wouldn't even grab on to the adjascent sections.
>2.) I changed the paraffin in the embedding station because I noticed all
>were set to 64 C when the melting point for the Surgipath paraffin formula
>'R' was 56-67C.
>Could this have been a problem?
>3.) I switched to an old lot of Fisher embeding medium and now all the
>section come off, but
>on occasion when the chuck on the mictomome comes back up it seems to (via
>electricity?) pull the ribbon from the microtome blade and interupt the
>4.) Also, visually the Fisher paraffin blocks look almost transparent
>whereas the Surgipath
>blocks seem opaque and white.
>I'm relatively new to the histology game and I realize that there is both
>art and science
>involved, but this is clearly unacceptable behavior from the paraffin,
>something is surely
>wrong. I'm sure you are all experienced and maybe you have advice? If
>you do I would
>apreciate it so much. The first and best advice get their choice of FTD
>flowers and/ or
>Thank you--Tyler Wellington
>Histonet mailing list
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-4303 (FAX)
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