RE: Carnoy's fixative II

From:Gary Gill

Posted previously by me in response to a similar request:

I'm aware of at least 3 formulations for Carnoy's.  Here's the 1957
modification from the National Cancer Institute:

*	95% ethanol			7 parts
*	Glacial acetic acid	2.5 parts
*	Chloroform			0.5 parts

I'm unaware of shelf-life limitations.  As long as hemolysis occurs and
there's no detrimental morphological changes, I don't see why it can't be
used -- regardless of age.  It should be used under a fume hood for obvious
reasons.  Immersion time should be limited to no more than 30 minutes.
Hemolysis may occur at different rates with different thickness
preparations.  Excessive shrinkage occurs; cells become noticeably smaller
in diameter and thicker.  Staining can be optically dense.  Discard after
use, as repeated use may diminish its hemolytic performance.

Transfer preparation to 95% ethanol after hemolysis is complete.  If a
specimen is very bloody, hemolysis in Carnoy's fixative will simply allow
you to see the remaining nucleated cells.  Your major concern should be
whether there are cancer cells in the raw specimen that aren't being seen on
the cell spread because the RBCs have crowded them out.  In such cases,
hemolysis should be performed while the cells are in suspension -- before
making the cell spreads.

Hope this helps.

Gary Gill

PS -- The original Carnoy's fixative was described first by Clark in 1850: 3
parts ethanol and 1 part glacial acetic acid.
In 1881, Frenchman Carnoy described: 6 parts ethanol, 3 parts chloroform,
and 1 part glacial acetic acid.

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