[Histonet] nail

Monfils, Paul PMonfils <@t> Lifespan.org
Mon Jun 13 11:24:36 CDT 2005

In sectioning nails, I use a combination of several procedures:

- a couple of drops of Nonidet P-40 in the water on the cold plate (I use
Tissue-Tek cold plates, stored in the -20 C freezer when not in use).  Soak
for 15-30 minutes before sectioning. (A couple of drops of liquid dish
detergent - not dishwasher detergent - could substitute).

- 10 to 20 ml PVA (polyvinyl acetate) in the water bath. PVA is quite
viscous and does not easily dissolve into the water bath.  To get around
this, I place a flask with 300 ml water on the hotplate stirrer at 70 C;
then while stirring, pour the PVA into the flask.  Let it stir for a couple
of minutes, then pour the contents of the flask into the water bath and stir
it in manually.  Rinse out the flask with hot water immediately because once
the PVA dries it is difficult to remove. The down side of using PVA is that
it makes the water bath "milky", so the floating sections are more difficult
to see.  But it does hold difficult tissues on the slides very securely, and
it causes a minimum of background staining with either immunohistochemical
or standard histochemical procedures.  Glues like "Elmer's Glue-All" and
"Sobo Glue" are good sources of PVA, and are cheaper then purchasing PVA
from a chemical company.

- a warmer than usual flotation bath, 70 C, to better flatten the sections.
This is warm enough to melt the paraffin, so you cannot place multiple
pieces of tissue in one block; but that usually isn't a good idea anyway
with such tough to section tissues.  Allow the sections to float for a few
minutes if necessary, until they appear flat.

- flattening and initial adherence of sections on an 80 C slide warmer for 5
minutes, after allowing slides to drain vertically for a couple of minutes.
Followed by standard drying in a 60 C drying oven for at least an hour.

	Paul M.

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