Re: "Venetian Blind" Artefact

From:"John C. Dennis" <>


The freeze artifacts I've seen in mouse and rat brain are round and make
the sections look like a mature swiss cheese.  My cryogenius sections
brain at just the temperatures you specify without problems EXCEPT when
we've failed to cryoprotect sufficiently.  I've rectified that problem by
cutting the brain hemispheres into smaller pieces to run through the
sucrose series.

I solved the venetian blind problem in paraffin by reducing the processing
time of the infiltration cycles.  I think I mean by that that venetian
blind effect is caused by at least hardening of the tissue and in your
case I would say overfixation may be a problem.  Squirrel brain may well
be different enough that different temperatures would be a
solution.  You'd hardly think so since they're really just cute rats.  But
now I'm rambling so I'll save you further time and stop.


John Carroll Dennis
Anatomy, Physiology, and Pharmacology
109 Greene Hall
Auburn University, AL  36849

On Fri, 12 Jan 2001, Stephanie Moore wrote:

> I have recently experienced what I believe to be this artefact while slicing
> sections of squirrel brain.  I know that this was not properly sunk and also that
> it was likely in too little volume of paraformaldehyde (4%) fixative.  The person
> who gave me the specimen is not very experienced, but wanted to slice it anyway.
> My question is, does insufficient cryoprotection from sucrose cause ventetian
> blinds?  I use a cryostat set at -20C chamber temperature and -18C object
> temperature, and Tussue Tek OCT medium for embedding the specimen.

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