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DIAGNOSTIC
METHODS:
Permanent Stains
Why
don't you need to use the iodine dish when staining fecal
smears prepared from specimens preserved in the newer single
vial systems (zinc sulfate based PVA)?
The
zinc-based fixatives do not contain any mercury compounds;
therefore, the iodine dish is not required for any chemical
exchange between the iodine and mercury. The zinc sulfate-based
PVA is water soluble, so the dry smears can be placed directly
into the trichrome dish without having to go through the iodine
and subsequent rinse steps. The zinc sulfate will be removed
by the water in the trichrome stain. |
