It is true that triglycerides do dissolve in the ethanol and clearing agents
during paraffin processing.  However, triglycerides are not the only "fat"
found in animal tissues.  There are many lipids bound to protiens, and they
may well resist extraction by xylene and other clearants.  The "fat"
component will indeed stain with fat dyes.  Lipofuscins come to mind.  In
fact, it is not uncommon to demonstrate some lipofuscins in paraffin
sections with oil red O.  Most of the methods used for frozen sections will
work, but it may be necessary to stain much longer than for those.  I use
oil red O saturated in propylene glycol for about two hours.

Bryan Llewellyn



---- Original Message -----
From: "Charles.Embrey" 
To: 
Cc: 
Sent: Tuesday, January 29, 2002 6:50 AM
Subject: RE: Oil Red O


> ORO for fat staining only realistically works on frozen tissue as fat
> dissolves in the clearing agent during processing.  Basic histotech 101
and
> a decent HT exam question.
> Chuck
>
> -----Original Message-----
> From: dgaupp@tulane.edu [mailto:dgaupp@tulane.edu]
> Sent: Monday, January 28, 2002 6:21 PM
> To: histonet@pathology.swmed.edu
> Subject: Oil Red O
>
>
> Hello Histonetters,
>
> Does anyone have a protocol for staining ORO on paraffin sections?
>
> Thanks,
>
> Dina
>
>