GEWF solution both fixes and helps to identify lymph nodes within adipose tissue. It is most often used in colon resections. This is a modification of the Lillie formula and alternative formulae with the same purpose have also been described.
Components:
(1) glacial acetic acid
(2) ethanol, absolute
(3) water, distilled
(4) formaldehyde, 37-40%
Reagent
GEWF Formula (v/v)
Alternative (v/v)
glacial acetic acid
6.25%
5%
ethanol
absolute 62.5%
95% ethanol 65%
water, distilled
water 21.25%
diethyl ether 20%
formaldehyde, 37-40%
10%
10%
where:
• The final formalin concentration should be 10% of the stock 37 to 40% formaldehyde solution.
The ratio of fat to GEWF solution is ideally 1 volume fat to 2-3 volumes of solution.
The tissue can be placed in the fixative overnight (12 to 18 hours).
Following fixation in GEWF solution lymph nodes appear as whitish nodules. The adipose tissue needs to be cut into thin slices (5-8 mm) because lymph nodes are often small.
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