I do not allow mega-cassettes in our lab. We have enought trouble getting
pathologists to cut tissue thin as it is.  Stuff is too thick to process
overnight as it is without them using huge cassettes. They think they can
toss big chunks of bone it these, fix, then decal..then trim, but by then
the bone is necrotic. Sometimes you have to take a stand..:)

-----Original Message-----
From: Gayle Callis [mailto:gcallis@montana.edu]
Sent: Wednesday, December 04, 2002 6:19 PM
To: histonet@pathology.swmed.edu
Subject: the pain of using mega cassettes


What is with the design of mega cassettes?  They DO NOT FIT into universal
clamping devices snugly.  There is always a gap at or between corners, far
less plastic, and create total havoc during sectioning.  We have some of
the first ones ever sold from Tissue Tek, an older than dirt lot #, that
work but still not a snug fit, although far better than a "newer to the
market lot" from another vendor - destined for garbage, unused!    

The garbage lot fit into universal clamp so poorly, one can't avoid block
instablilty, leading to chatter, chopped blocks, etc and reorientation is
impossible (if we need to change) they literally fall out of universal
clamps. One can move a megacassette block from side to side freely when it
is in the clamp, a painful ugh!    

We have resorted processing with garbage megacassettes (large, thick
samples) but embed in Peel a away molds, 22 X 40 and push a regular plastic
cassette back down to the sample, this reduces overall block size sticking
out horizontally towards knife, but regular cassette backs FIT in block
holders. Double the cost and work to have stability. 

Hopefully, vendors are looking in, and take it to heart about getting the
little monster megas to fit into a block clamp properly.  Are these mega
monsters EVER tested in the various universal clamps for the many
microtomes out there, or just an educated (??) guess/copy cat design about
the fit? 

Ho hum





 
Gayle Callis
MT,HT,HTL(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology - Marsh Lab
Montana State University - Bozeman
S. 19th and Lincoln St
Bozeman MT 59717-3610

406 994-6367 (lab with voice mail)
406 994-4303 (FAX)

email: gcallis@montana.edu