RE: Alcohol for Processing
In my cytological experience, isopropanol shrinks cells more than does
ethanol (contrary to Paul's comment), which in turn shrinks cells more than
does methanol. I suspect the same is true for tissue.
Think of alcohols as organic derivatives of water (i.e., H-OH [H2O]). The
longer the chain length, the more unlike water the alcohol becomes, and the
greater the differences observed in dye solubility for stains and rinses and
in fixation. MtOH, EtOH, and IPA each has 1, 2, and 3 carbons,
From: Paul Bradbury [mailto:firstname.lastname@example.org]
Sent: Friday, April 18, 2003 10:16 AM
To: HistoNet Server; Laurie Colbert
Subject: Re: Alcohol for Processing
You can use any of the three alcohols you have. However, the final sequence
of dehydrating alcohols must be completely water-free. Terminology may vary
but you need 100% , pure, absolute, anhydrous, etc.
I assume that you are using xylene as your clearing agent. Xylene is
non-miscible with water, so all traces of water must be removed from your
tissues ... the alcohol you use for dehydrating must be completely
water-free, if not, the xylene will not penetrate fully, this will prevent
the wax from penetrating, etc.
Ethanol, methanol, and your reagent alcohol will work at much the same
speed, so no changes to your time schedule should be needed. Isopropyl
alcohol (rubbing alcohol) is known to be a somewhat slower dehydrating
agent, so slightly longer treatment in the dehydrating alcohols will be
needed. Isopropyl alcohol has also been described as causing less shrinkage
and less hardening than ethyl alcohols.
So, you have all the reagents that you need to continue processing. Just
make sure that the final dehydrating alcohols are free of any trace of
water. You could even use acetone as the final dehydrant if you have any.
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