A device for mounting a living (or otherwise shape-changing or moving) specimen in a chamber for microscopic examination, the device comprising: a first part for mounting the device in or on the chamber; an inlet port for receiving a flow of a liquid medium; and a second part attached to the first part, the second part being arranged to extend into the chamber in use and to form a substantially straight channel between the second part and one or more walls of the chamber, the channel being for constraining the specimen in use; wherein a first conduit extends from the inlet port, through at least part of the second part, to an outlet hole in the second part, for conveying the liquid medium into the chamber via the outlet hole. Also provided is an assembly comprising such a device mounted in a chamber, and a method of examining a specimen using such a device.