Our laboratory has become interested in how to adjust the
osmolarity/osmoality of fixatives.  We conduct neurotoxicity studies
with rodents.  The animals are currently perfused with the 10% buffered
formalin after a flush with sodium nitrite.  We have recently identified
vacuoles in the peripheral nerves (sciatic, tibial, sural and spinal
nerve roots) which are embedded in glycol methacrylate.  We do not see
this artifact in the tissues embedded in paraffin.  Some of our
pathologists believe this is due to the high osmalitity found in our
purchased fixative.  We understand that the recommended range is 400-600
mOsm.

Does anyone have experience with adjusting the osmoality of fixatives?
Are there references that may help us to better understand this and how
to make the adjustments?  Is this artifact possibly caused by something
else?  If you can provide some answer to these questions please contact
me.

Joyce Christopher
Bayer Corporation
913-433-5244
joyce.christopher.b@bayer.com