Re: Wavy sections

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From:"J. A. Kiernan" <> (by way of histonet)
To:histonet <>
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On Mon, 14 Dec 1998, Marilyn Woods wrote:

> Looking for suggestions on the cause of wavy sections, so bad that we are
> unable to focus under high power.  This has happen out of the blue without
> changing any procedures.  I am cutting all skin, some look good,  but this
> problem seems to affect the staining ex. muddy appearing, poor contrast and
> understaining.  All temps. are with norm. except of a paraffin bath on
> processor is 64 C. Sections have been good 2 days a week then progressively
> get worse.

   Your use of the word "wavy" suggests that the thickness varies,
   in stripes or bands parallel to the knife edge, or that wrinkles
   were not flattened out. The former is more likely because you
   would have seen failure to get rid of wrinkles. The artifact of
   thickness varying as the knife cuts through the block is called
   "chatter." Perhaps this is what you have. It is attributed to
   vibration of either the knife edge or the specimen, and the
   remedy is to tighten everything up on the microtome, including
   the little screws that hold a disposable blade onto its support
   (if applicable to your equipment).

   For an excellent account of chatter and many other cutting artifacts,
   see "An Introduction to Histotechnology" by Geoffrey Brown (Appleton
   Century Crofts, New York, 1978. ISBN 0-8385-4340-5). I don't know
   if it's still in print. I found my copy quite recently, by chance,
   in a second-hand bookshop, having been previously unaware of it.
   This nice hard-cover volume may not have got enough publicity. The
   practical instructions and hints about details are first rate. The
   author evidently draws on experience in the U.K. and U.S.A.

   This may not answer your question fully, because even uneven sections
   and those with chatter can be brought into focus if the microscope
   knob is continually adjusted while moving across the field. Maybe
   more than one factor is involved, but something wrong in the cutting
   is probable on the strength of what you say.

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1

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