Dear Tony.
as a rough rule of thumb (no pun intended), compression usually means that your cabinet and knife are too warm, while fracturing means too cold. An old way of coping with such tissues is to deliberately make the conditions too cold, face the block, then attempt to section. If it fractures slowly wipe your thumb across the surface and attempt to section again until you are achieving reasonable sections- just make sure you discard the first successful section and take the second or third as the first will be too thick.
I've found this works esp. well for testicle, thyroid and other tissues prone to fracturing.
PS make sure you wear a glove or you might loose a layer of skin, not to mention risks of infection.
Best regards Mike Rentsch. (Downunder)

-----Original Message-----
From: tony.whyte <tony.whyte@bbsrc.ac.uk>
To: Reply requested <histonet@pathology.swmed.edu>
Date: Thursday, 9 March 2000 3:28
Subject: Cryosectioning


>Hi all,
>
>i'm having trouble sectioning whole frozen mouse embryos.  They were snap
>frozen in isopentane in liq N2 and mounted in OCT on cork.  The trouble is
>either that the section is compressing or else fragmenting.  Using a new knife
>hasn't helped the problem.  Any ideas?
>
>Tony W.
>Cambridge
>
>