Cell counters and methods of their use are disclosed herein. The cell counters comprise a sample mounting system that includes a base comprising a mounted lower sample surface and a cover comprising a mounted upper sample surface; a bright-field light source incorporated in the cover; an objective lens mounted below the sample mounting system; optionally, a fluorescence excitation source in optical communication with the sample mounting system; and an imaging system in optical communication with the bright-field light source and the objective lens. The mounted sample surfaces are configured for repeated use, such that disposable sample cartridges are not needed.