An indexing stage for microscopic scanning of microtitre tray wells

A simple stage has been designed to hold and to move microtitre trays for examination under a low power dissecting microscope. Movement of a ball on a handle from well to well of a reference tray to the left of the stage is mechanically translated into movement from one well to another under the microscope field. Movement can be controlled entirely by touch, and the particular well under the field can be determined from the reference tray position. The flat bottoms of all 96 wells stay in alignment and in focus without further adjustment, enabling rapid scanning of all wells on a tray. The apparatus is particularly useful for the microtitre tray antibody-forming cell plaque assay described by Pike et al. (1982).