> ----------
> From: 	J. A. Kiernan[SMTP:jkiernan@julian.uwo.ca]
> Sent: 	Tuesday, January 11, 2000 10:39 PM
> To: 	Linda Prentice
> Cc: 	histonet@pathology.swmed.edu
> Subject: 	Re: OCT: What's in it? Is it good? Etc (Rather long)
>
	-snip snip-

>   Unfortunately the identity of OCT isn't stated on the
>   squeezy-bottle, and the same is true of other brand-name
>   products that do the same job.
John,
My squeezy-bottles of O.C.T.  state the following: "Contents: 10.24% w/w
polyvinyl alcohol; 4.26% w/w polyethylene glycol; 86.50% w/w nonreactive
ingredients."
> A reasonable guess might
>   be that they contain water and polyethylene glycols of
>   quite high molecular weight. Gelatin (about 2% in water)
>   seems to work about as well. Some HistoNet discussion in
>   the past indicated that the initials stood for Optimum
>   Cutting Temperature. This makes no sense in the context
>   of cryostat sectioning, but it may do so if you are using
>   an old-fashioned open-air freezing microtome (as do many
>   of us who work with thickish sections of CNS, muscle or
>   skin for research purposes).
The name O.C.T. may make no sense in your context, but the squeezy-bottle
also states, "Freeze to optimal cutting temperature." I've also understood
the name to be an acronym for Optimal Cutting Temperature, but perhaps some
former Tissue-Tek person or one of the Sakura people could enlighten us
further. I think we all know that product brand names don't always follow a
totally logical convention. I've tried both water and O.C.T. for frozen
cryostat sections and definitely prefer O.C.T.

John Tarpley 15-2-B
Associate Scientist
Specialist Image Analysis & Immunohistochemistry
Amgen Inc
One Amgen Center Drive
Thousand Oaks, CA  91320