Dear Margaret,

	The problem you are facing is that there is simply too much material there
to allow simultaneous freezing of the whole specimen.  You will find that
while you can get rapid freezing of the surfaces of the specimen the centre
will freeze very (relatively) slowly resulting in the formation of massive
ice crystals which will distort the shape of the entire sample.

	You could try pre treating your specimen with a cryoprotectant ( ie a long
soak in a high concentration of sucrose solution), & even then the results
would not be good.  The idea here is that the sucrose in the specimen
disrupts the formation of large ice crystals.  There are 2 mechanisms, 1
the freezing point of water is greatly reduced, 2 the presence sucrose
molecules physically prevents the formation of large ice crystals.

	Your best alternative, & morphologically this could be quite poor, is to
freeze very slowly, like the meat in the freezer at home.  

	Regards
	
	Rob W.

At 08:10 AM 7/13/99 -0500, you wrote:
>Hi All-
>In light of all the recent talk (and great tips) on muscle techniques, I
>thought I would post this question.  I routinely work with large animal
>muscles.  Currently, I am only freezing down small muscle samples.  I would
>love to be able to do a cross section of a whole muscle.  I'm thinking
>along the lines of a pig tibialis or gastroc muscle.  At it's widest part,
>a pig tibialis (from the animals that we use) is about 3cm by 2 cm.  How
>would one go about freezing down a section that thick while minimizing
>freeze artifact?


R. Wadley, B.App.Sc, M.L.S
Laboratory Manager
Cellular Analysis Facility
School of Microbiology & Immunology
UNSW, New South Wales, Australia, 2052
Ph (BH) 	+61 (2) 9385 3517
Ph (AH)	+61 (2) 9555 1239
Fax 	+61 (2) 9385 1591
E-mail	r.wadley@unsw.edu.au
www	http://www.micro.unsw.edu.au/caf.html