[Histonet] Oil Red O

[Monfils, Paul]

Oil Red O slides will never "fade".  The technique isn't like typical
histochemical procedures where dye molecules bind chemically to tissue
components.  In Oil Red O staining there isn't any chemical binding that
can be reversed.  What you end up with is a solution of the dye in the
fat droplets.  Once coverslipped with an aqueous mounting medium, the
dye cannot escape from the fat droplets because it is insoluble in
water.  Therefore the dye in the fat droplets is just as stable as the
dye solution in the bottle, and the slides will remain good as long as
the coverslipping medium doesn't dry out - which in this case is the
reason for refrigeration, to slow the drying of the mounting medium.