Date sent:      	Wed, 28 Feb 2001 18:32:23 +0000
From:           	frank quin <fquin@hotmail.com>
Subject:        	mouse embryos - frozen sections
To:             	histonet@pathology.swmed.edu

> Anybody have any tips on sectioning whole mouse embryos?  I'm embedding them 
> in OCT at -20 C and they are sectioning OK, but the sections don't stay 
> together. They split and do not remain contiguous.  This isn't a knife nick 
> problem, but probably results from the different densities of the various 
> organs.

Frank, are you dealing with fixed or unfixed material?
I have found that fixed embryo's that have been in-situed
cut best when soaked overnight in 20% sucrose, embedded in 
OCT, then "snap" frozen in liquid N2.
Allow the tissue to equilibrate to cryostat temperature and cut at 
about -10oC (specimen temp.), knife temperature -12 to -15oC.
This should eliminate any damage to the embryo and allows serial 
sectioning.
Unfixed tissues can be more of a problem and depending on the 
technique to be used may not allow any sucrose treatment. Again, 
do not cut them too cold.
Terry.

Terry Hacker,
Medical Research Council,
Harwell,
Didcot,
Oxfordshire, OX11 ORD
01235 834393 x360