Staining, Histochemistry and Histotechnology
(Frequently Asked Questions)
Dr. John A. Kiernan
Department of Anatomy
and Cell Biology
The University of Western Ontario
Cutting sections of toe or finger nails
Does anyone have a few hints for sectioning toenails?
[Here is a selection of many replies to this frequently asked question. ]
10% Potassium hydroxide. Soak them for at least 4 hrs, but not more than 8.
Noreen S. Gilman (n4xiu[AT]gate.net)
I have not cut toenails for years. (I do cut my own personal toenails of course!) However, we used to soak them for a short time in Nair, which i believe is like Neet, and we got an excellent section. [See also Answers 4 and 5.]
The procedure is to process the nails, and after they are embedded treat the paraffin block by putting it in a petri dish containing the Nair. The Nair is put in first and then the block is put on top. We treat the block for 5-10 minutes depending on the size of the nails. We wipe off the block, try cutting it and put it back for further treatment if needed. It is best to cool the block on iced water after treatment and before cutting and to take the first sections.
I learned a new technique at one of the outstanding workshops at NSH-Albuquerque. Our hospital switched to this method. After grossing, place a representative piece (or ALL if melanoma is indicated) in a cassette and immerse the nail in 5% Tween 80 (Sigma cat#P-4634) for 1-2 hours at least. Overnight won't hurt it. Then remove and process as usual. I find that if you orient the nail to cut it perpendicular to the knife it cuts more easily. Use a charged or polylysine slide (or Elmers glue if it's really likely that it will float).
Albany Medical College
There are several methods in Luna's last book "Histopathologic Methods and Color Atlas of Special Stains and Tissue Artifacts" for softening keratin in nails, etc. Fixation in 10% buffered formalin is necessary to produce crosslinking and thereby prevent keratin from dissolving completely in softening solutions. After fixation and BEFORE processing -- place specimen in "Neet" or other depilatory cream or permanent wave solution for one to several hours. The key ingredient in these solutions is thioglycollate. * This is best performed under a hood because these products smell really bad and will guarantee an increase in lab traffic by interested personnel wanting to know "What on earth are you doing?" The specimen should bend easily before continuing with next step. Wash the specimen in running tap water for 10 minutes. Dehydrate, clear, and impregnate with paraffin as desired. Processing times will depend on which hoof you are processing -- elephants take a lot longer than goats :-) Get out your nose clip and have fun!
We have routinely used "Neet" overnight and had good results. Recently tried "Neet" at 58 C (it liquefies) for several hours during the day on a particularly tough nail; it cut beautifully the next day!
St. Joseph's Health Centre
London, Ontario, Canada