Re: [Histonet] Sliding vs. Sledge Microtome

From:Bryan Llewellyn

I learned to section on an MSE base sledge microtome many years ago, as did 
most British technologists of the time.  Not only is the knife fixed it is 
also clamped in place.  The tissue is also clamped onto a stage which could 
move back/forward by pushing, and up/down on a screw thread keyed to the 
back/forward movement or by releasing a spring closed clamping nut.

The sliding microtomes which I have used had fixed, clamped tissue on a 
fixed stage keyed to the knife movement and also up/down by a screw thread. 
The significant difference is in the knife.  It was clamped into a holder 
with an offset V-shaped bottom which rested in a complementary shaped groove 
by weight alone with no clamping.  If a hard tissue was struck (calcified 
tissue), the knife holder would jump since it was not clamped to the main 
body, but held in place by gravity and perhaps a small lip on top of the 

The microtomes were operated differently.  The sledge usually was used with 
a wedge shaped knife with a fairly short distance between edge and back so 
that it was very rigid.  A small slant was used on the knife, but mostly a 
small area was used by pushing a paraffin block across the edge and peeling 
the section off.  One of the hazards was pushing the block too far too fast 
and nicking the fingers and nuckles, as the scars on my right hand testify.

The sliding microtome usually used an extra plano-concave knife which was 
fairly wide and very thin along the cutting edge.  It vibrated very easily 
and could not take too much force applied to it before it chattered.  It was 
not usually used with paraffin blocks because they chattered too easily.  It 
was more commonly used for celloidin sectioning at 15-20 microns.  The knife 
was slanted enough so that the whole edge was used to cut each section, and 
it was sliced off the block instead of peeled.  It took a lot of practice to 
use this microtome effectively, and I never did enough of it to become 
really adept.

Thanks for the trip down memory lane.

Bryan Llewellyn

----- Original Message ----- 
From: "Charles Scouten" 
To: ; 
Sent: Monday, March 28, 2005 9:48 AM
Subject: RE: [Histonet] Sliding vs. Sledge Microtome

Your definition conforms to what I have seen, that sliding means moving 
blade, and sledge means moving tissue.  However, I do not think there is any 
functional difference.  They can be used for all the same applications, are 
both grouped under the category "sliding microtome".  Does anybody in 
histoland who has used both feel they have different applications?  There is 
a clear safety difference, but the tissue doesn't care which moves.

Charles W. Scouten, Ph.D.
5918 Evergreen Blvd.
St. Louis, MO 63134
Ph: 314 522 0300
FAX 314 522 0377

-----Original Message-----
[] On Behalf Of
Sent: Friday, March 25, 2005 5:20 PM
Subject: [Histonet] Sliding vs. Sledge Microtome

Help me out here.
What is the generally accepted distinction between a sliding and a sledge
microtome?  It seems to me that the terms get used interchangeably.   In my
book, a "sliding" microtome has a fixed specimen holder and the knife 
slides back and forth on a slide way.  It is used for routine or frozen 
sectioning of samples.  A "sledge" microtome has a fixed blade and the 
specimen is moved, either manually or motorized.  The general application 
is for hard samples such as bone and in some material science  applications.
Any comments can be sent to me directly if you would like.
Dorothy Murphy Traczyk
Hacker Instruments & Industries Inc.
PO Box 1176
Winnsboro, SC 29180
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