DIAGNOSTIC METHODS: Permanent Stains

Tips and Pitfalls

1. If the smear under the coverslip appears very refractile, dehydration may have not been sufficient (change reagents: 100% alcohols, xylene substitutes). Remember, these xylene substitutes do not dehydrate the specimen as well as xylene, but for safety reasons, xylene substitutes are recommended.
2. The color range of organisms stained with Wheatley's trichrome varies tremendously; different colors do not indicate problems with the stain unless everything (background organisms) stain uniform pink or red (change reagents, specimen may not have been well preserved).
3. Stained smears do not have to be coverslipped using Permount prior to examination. Take the slides out of the last dehydration reagent and allow them to dry. About 10 minutes prior to examination place immersion oil (one-two drops) onto the dry smear and allow the oil to sink into the fecal film. Immediately prior to examination, add a #1 coverslip (to protect the oil immersion lens), add a drop of immersion oil to the top of the coverslip, and examine as usual.
4. Strong light should always be used to examine all stained fecal smears (condenser should be up as far as possible).