Degreasing

Degreasing is a technique used primarily in some of the more demanding trichrome methods for the demonstration of fibrin, but the general principles are applicable to many trichrome methods. The process removes lipid materials associated with tissue components which can inhibit penetration of aqueous fixatives and dyes. Secondary fixation of sections with a strongly precipitant fixative is an integral part of the technique.

Method

1. Cut paraffin sections at 3-5 microns
2. Remove paraffin wax with xylene
3. Rinse with trichlorethylene
4. Place into a tightly closed container of trichlorethylene for 72 hours at room temperature
5. Rinse with three changes of absolute ethanol
6. Refix sections for 48 hours in picro-mercuric-ethanol at room temperature
   (Saturated mercuric chloride and picric acid in absolute ethanol)
7. Rinse well with water
8. Remove mercury pigment with the iodine thiosulphate sequence
9. Wash well with water, and stain.

 

Reference
Lendrum, A.C., Fraser, D.S., Slidders, W., and Henderson, R. (1962)
Studies on the character and staining of fibrin,
Journal of Clinical Pathology, vol. 15, p. 401