Solutions: Thionin: thionin, C.I. 52000 1.0-2.0 gm. Distilled water 100.0 ml. Orange G: orange G, C.I. 16230, saturated solution in oil of cloves. It goes into solution slowly; stir frequently. Allow to stand 24 hours before using. Good until it becomes discolored by thionin.
1. Deparaffinize and hydrate slides to water; remove HgClo.
2. Stain in thionin: 2-3 minutes for light stain; 10-15 minutes for an intense stain.
3. Rinse briefly in water for light stain; blot around sections for in tense stain.
4. Dehydrate by dropping a few drops of absolute alcohol on sections.
5. Stain with orange G-clove oil: 1-2 minutes. Repeat orange G until thionin disappears from cytoplasm, leaving it orange. Mast cells remain unchanoed.
6. Clear thoroughly in xylene, and mount.
Results: mast cells — deep blue or purple blue cytoplasm — light gold-orange nuceli — faint blue