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.
Bob Waterston



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