A co-axial mechanical stage is a laboratory instrument used in microscopy to hold and move specimens on a microscope slide. Unlike a detachable mechanical stage, the co-axial stage is permanently attached to the microscope stage and moves in two perpendicular directions using co-axial controls. This allows for precise positioning of the specimen under the microscope objective for examination and analysis.

The co-axial controls are located on the same axis as the microscope focus controls, which makes it easier to manipulate the position of the specimen while maintaining focus. The mechanical stage typically includes a vernier scale or other measuring device to aid in accurate placement of the specimen.

The co-axial mechanical stage is commonly used in research and clinical laboratories for a variety of applications, including histology, pathology, and microbiology.