Shrinkage in EM?
Shawn Lockery 503-346-4590
shawn at chinook.uoregon.edu
Wed Dec 28 12:46:11 EST 1994
/* Here are the answers to my question about EM shrinkage. Thanks to
those who responded. */
:Shawn Lockery 503-346-4590 (shawn at chinook.uoregon.edu) wrote:
: For a paper on C. elegans electrophysiology, I sorely need to know the
: diameter of the processes of particular neurons. Unfortunately,
: tissues shrink substantially when prepared for EM, and the White et
: al. 1986 paper does not report the amount of shrinkage.
: Does ANYBODY know, or know somebody that knows? Process diameter has
: a huge effect on expected passive electrical properties.
: Thanks in advance!
: Shawn Lockery
From: "Dr. David Hall" <hall at aecom.yu.edu>
This is the kind of question one often acknowledges as important, but never
really adresses fully, until forced to. There must be some shrinkage,
maybe as high as 20-25% (ouch!), but I've never pursued the ugly truth.
One needs a standard unshrinkable object to co-embed with a worm, having
compared their dimensions before fixation and embeding of the worm, and a
very precise means of measuring both by some LM technique. There is also
some compression of the worm during sectioning, leaving the animal looking
somewhat elliptical in cross-section, but I always re-expand the sections
by exposure to chloroform vapors, which allows the sections to pop back to
a non-compressed state with round profiles (but are they now bigger than
before sectioning???). I've never done the expreiment.
From: "David L. Baillie" <dbaillie at darwin.mbb.sfu.ca>
As i recall when I worked with Sydney, there was not ver much shrinkage.
Do you really have to know, if it is say 10-20%? If so I would e-mail
Bob waterston at Wash U. dept of Genetics, he will know the answer.
From: rw at elegans.wustl.edu (Bob Waterston)
I don't remember ever measuring shrinkage directly. Certainly by filament
diameters and A- and I- band spacing there is not much shrinkage. For
example you might look at an early Mackenzie and Epstein paper on striations.
Otherwise I can't help.
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