DIRECT WET SMEAR: Introduction (cont.)

morphological detail is more readily seen by oil immersion examination of the permanent stained smear. This is particularly true in a busy clinical laboratory situation.

The direct wet mount is used primarily to detect motile protozoan trophozoites. These organisms are very pale and transparent, two characteristics that require the use of low light intensity. Protozoan organisms in a saline preparation will usually appear as refractile objects. If suspicious objects are seen on high dry power, allow at least 15 s to detect motility of slowly moving protozoa. Heat applied by placing a hot penny on the edge of a slide may enhance the motility of trophic protozoa. Tapping on the coverslip can also stimulate the fluid to move; objects will roll over, thus providing a better view of the parasite or artifact. After the wet preparation has been thoroughly checked for trophic amebae, a drop of iodine can be