hanging drop preparation [ME, hangen, to hang; AS, dropa, to fall; L, praeparer, to make ready] , a technique used for the examination and identification of certain microorganisms, such as spirochetes or trichomonads. The technique requires a coverslip, a microscope, and a special slide that has a central concavity. A specimen suspected of containing the microorganism is diluted with a sterile isotonic solution. A drop of this fluid mixture is placed on a glass coverslip, which is then inverted carefully and placed over the slide so that the drop is hanging from the slip into the concavity in the slide. The delicate structures and the method of movement characteristic of the species may then be viewed through the microscope.
