Since the PTI is attached to an inverted microscope, there is one important constraint -- if the oil immersion objective is required for sample analysis, e.g., for enhanced fluorescence detection, the bottom of the culture dish must not be thicker than a #1 cover glass. Provision can be made for samples on slides or in Petri plates. Please check, however, to make sure your sample is in the proper configuration before bringing it to the Research Cytometry Laboratory (RCL). For first-time experiments, consult with the RCL before preparing your cultures.