[Histonet] Rat eyes in paraffin

Monfils, Paul PMonfils <@t> Lifespan.org
Mon Dec 19 14:33:59 CST 2005

Assuming that you will be sectioning the eyes in the sagittal plane, try
making a small incision on one lateral side of the eyeball with a #11
scalpel blade. Immerse the specimen in a petri dish or other shallow
container before making the incision, and don't hold the specimen with
forceps when making the incision, Otherwise the pressure of the forceps will
collapse the specimen, forcing fluid out through the incision. This will
allow freer flow of solvents into and out of the sphere, and will thereby
avoid the buildup of differential pressure that occurs when one solvent
diffuses through the wall faster than the other, which is what causes the
collapse.  Of course, if you are sectioning in a plane other than sagittal,
just make the incision on a part of the eyeball that won't appear in the
actual section.  If the collapse occurs at a specific point in the process,
such as just after the switch from 100% alcohol into toluene, then make the
incision just before that switch, in this example while the specimens are in
100% alcohol.  The hardening effect of the dehydration will make it easier
to cut the incision.  It is more difficult to cut the fresh, unfixed
specimen because of the softness of the tissue.  I notice you do not use
formalin, and I assume there is a reason why you don't.  However, the
hardening effect of formalin also helps protect against collapse as well as
facilitating the cutting of an incision.  This method works well on various
kinds of whole, hollow specimens such as gallbladders or urinary bladders,
swim bladders of fish, cysts of various kinds, etc.
> ----------
> From: 	histonet-bounces <@t> lists.utsouthwestern.edu on behalf of A.
> Erickson
> Sent: 	Monday, December 19, 2005 11:29 AM
> To: 	HistoNet Server
> Subject: 	[Histonet] Rat eyes in paraffin
> Hi all,
> I have a problem when blocking the rat eyes in paraffin. The eye tend to 
> colapse and what I need is the round eye.
> My paraffin procedure is fix the eyes for 15 minute in 70%, 80%, 95%, 
> 100%, mix 100%+Toluene, 2X Toluene. Then 30 minutein mix 
> Toluene+Paraffin, Paraffin, Paraffin+vaccum.
> Most of the eyes were colaps. Is anyone has another protocol to prevent 
> the colapsing of the eyes?
> Thank you so much.
> Regards,
> Dayat
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