We have found that when CO2 is used for euthanasia, the lungs have some
degree of hemorrhage.  If this procedure is used for all animals, then this
shouldn't be a problem.  This method of euthanasia should have no impact on
the fixation, as long as the tissues are small enough and are placed in
sufficient volume of fixative in a timely manner.  As long as you also
perform exsanguination of the animal when you open the abdominal cavity (by
incising both the abdominal aorta and posterior vena cava) there should not
be problems with formalin pigment in the spleen (by removing 'most' of the
blood).  Also make sure to use buffered formalin.  It shouldn't matter what
type of mouse you use.  If you have any more questions, please let me know.

Barb
Supervisor, Histo/Necropsy
Glaxo Wellcome


> -----Original Message-----
> From:	Hawkins, Hal [SMTP:hhawkins@SBI.UTMB.EDU]
> Sent:	Monday, March 29, 1999 6:18 PM
> To:     'histonet 
> Subject:	preservation of mice
> 
> 
> 
> A question for the group.
> I'm planning an experiment in which mice will be killed and the
> lungs and several other organs examined histologically.  Some of
> the mice will be transgenic.  The question is, would killing the
> animals with CO2 narcosis have an adverse impact on the quality
> of preservation, e.g. generating formalin pigment in the spleen?
> Does anyone have experience with this method?
> 
> Thanks in advance
> 
> Hal Hawkins
> UT Medical Branch, Galveston, TX  
>