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A simple microtitration-plate holder for use with an inverted microscope.

Microtitration methodology has become popular in recent years for virus titration and serological procedures (1,2,3,5). Many of the avian viruses have been adapted successfully for growing in cultured cells, lending these adaptable to microtitration methods. There have been a number of reports in recent years of the use of microneutralization tests with avian viruses (4,6,7). An inverted microscope (Olympus Model IMT, ActinoRex, Inc., Springfield, Mo.) was recently purchased for use in our laboratory. One of the criteria used for selecting the microscope was that it have a mechanical stage, and that this stage be compatible with standard 12.7 cm X 8.5 cm 96-well microtitration plates (Falcon Plastics, Oxnard, Calif.). There was no standard-accessory microtitration-plate holder available for the inverted microscope, but a device could be made that would work with the standard-accessory mechanical stage (Olympus IMT-MVR). The simple microtitration-plate holder was machined from a piece of 3-cm-thick brass plate, and is depicted in Figs. 1, 2, and 3. The only modification was a slight enlargement of the mechanical stage by filing to hold the plate. The only inconvenience in using this accessory is in vertical movement. The stage will move the plate only to the sixth well. All 12 wells in a row can be observed, however, simply by reversing the plate in the holder. The lateral movement of the mechanical stage is sufficient to cover the full width of the microtitration plate.