[Histonet] Marking Tissues with Eosin

[Bob Richmond]

Rebecca Ashley at the Wyoming State Vet Lab in Laramie asks >> I had a
biopsy today that was nearly impossible to see on the sponges during
embedding or in the block. I've heard mention of marking these with eosin
to make them easier to see. Has anyone done this? Or do you use some other
type of marking dye for this purpose?<<

You must not use eosin (or other fluorescent dyes such as Mercurochrome) to
mark tissue during grossing - the persistent dye interferes with FISH - you
don't want eosin in your tissue processing system at all.

As Cindi (where?) notes >>We use safranin at the grossing station and it is
a dark pink at embedding. Works really well in our hands. Added plus is no
fluorescent issues that you can have with eosin.<<

I've found safranin O (not saffron) to be highly satisfactory, and it is
not fluorescent. A solution of it is used by microbiology labs as the
counterstain for the Gram stain, and this preparation is highly
satisfactory and you don't have to buy anything if the lab across the hall
already has it.

I've heard of using hematoxylin for this purpose, but have never seen it
done.

Bob Richmond
Samurai Pathologist
Maryville TN