re: CWD brain tissue lifting off slides

From:Jan Shivers

We're having trouble keeping our CWD brain tissue on the glass slides during
the IHC process.  I would appreciate any helpful hints (ASAP) that anyone
could send my way.

This is what we're doing so far:

Tissues are fixed in NBF for 24 hours; put into 98% formic acid for 1 hour;
transferred to fresh NBF for 48 hours before processing.
Slides are sectioned at 4 microns and placed on poly-L-lysine coated slides.
Slides are air-dried for 1/2 day.
Slides then go into a 56C oven overnight and begin the deparaffinization
process the next morning.
After going through the solvents/graded alcohol series/dH2O, they are dipped
in 98% formic acid again for 5 minutes and rinsed in TBS x3 before HIER.

I've noticed that the tissue has begun to come off the slides DURING the
deparaffinization/rehydration steps, so I'm thinking that it has something
to do with the fixation process or inadequate adherence to the slide, and
not due to HIER.  What comes off first is the center of the tissue pieces,
but the pieces are not extraordinarily large.  Most are between dime and
nickel size.

Also, the microtomist is putting ammonia (but nothing else) in her water
bath.  Would this interfere with section adherence?

Is the 1 hour in formic acid just chewing up the tissue so badly that not
much is able to adhere?

CWD pros out there.... what tricks to you employ?  Thanks in advance.

Jan Shivers
IHC lab
Univ of Minn Vet Diag Lab

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