[Histonet] OCT definition

[Gayle Callis]

Optimal Cutting Temperature, clearly stated on the dispensing bottle.  Dr.
McCormick was in on the development of this cryoembedding media with Miles
aka Tissue Tek, now Sakura Finetek.  The bottle also says it contains
polyvinyl alcohol, polyethylene glycol and inert ingredients. The PVA and
PEG concentration and molecular weights are proprietary. 

Via private discussion with him, he said one could adjust the PVA and/or
PEG to give different cutting qualities at different temperatures and
different hardness to the media. The mixture we buy today is what they came
up with.  It has a good temperature range  (we use anywhere from -16C to
-35C).  It is designed to surround the tissue for support and not
infiltrate (as one does with paraffin).  Some do this, but it must be
pointed out the if the MW of the major ingredients is large, infiltration
would probably be minimal.  

Interesting, I have never been asked to define OCT in great detail for any
publication!  Usually it is stated tissue placed in O.C.T. cryoembedding
media (be sure to put in trademark, Sakura Finetek, Torrance CA) and snap
frozen at certain temperature. Methinks your editor asketh for too much
when it is not really necessary to explain OCT is such detail.   


Gayle Callis
MT,HT,HTL(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology 
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367 (lab with voice mail)
406 994-4303 (FAX)