We are currently sectioning perfused rat brains at 40 microns with a Leica
SM2000 (purchased in 1996).  Immuno staining is performed with floating
sections in wells with excellent results.  However, our scientist are
constantly complaining of section thickness variability.  This became a big
issue when we needed to calculate graft volume( we are transplanting cells
in the rats brain).  I contacted Leica about whether or not the machine was
sectioning properly and they alluded to the fact that that particular model
which I purchased was no longer made because of automatic advance problems.
The machine was sent back and according to Leica was repaired. The scientist
are still complaining inspite of the repair.  My question is :  Could
section thickness variability be a result of the machine not working
properly or is it because of the freezing platform temperature( we never
have trouble getting "nice looking" sections) ?  Has anyone else experienced
this problem?
Any advice would be greatly appreciated.

Joyce Bousquet
Diacrin
Boston, MA