From Big Medical Encyclopedia

HANGING DROP — a method of preparation of drugs for studying under a microscope of microbes In a live state. It is entered into microbiological practice (1876) by R. Koch. Allows to observe reproduction of bacteria, the nature of their movement, development from a dispute of vegetative forms, the phenomena of a chemotaxis, effect of immune serums and so forth. It is used during the studying of morphology of protozoa, spirochetes, yeast and mushrooms. Usually investigate young (for a bacterium 24-hour) the culture which is grown up in fluid or dense medium. In the latter case previously prepare a suspension of microbes in isotonic solution of sodium chloride or use water of condensation. The suspension shall not be very dense.

The small drop of the studied material is applied with a loop or a pipette on the middle of the pure, but not fat-free cover glass. A slide plate with deepening («hole»), edges to-rogo are greased with vaseline, is carefully imposed on cover glass so that the drop of the studied liquid was in the center of deepening, densely nestles on glass and then quickly turns up. The drop of culture shall hang down freely in space of a hole. It is possible to impose cover glass with the studied material on subject. Greasing of edges of a hole vaseline creates tightness of the camera, protecting drug from the drying leading to more bystry dying off of the studied microorganisms. A lack of a method is lack of clearness of contours of observed objects owing to curvature of the hole preventing, in particular, obtaining high-quality photos. Instead of slide plates with holes for V.'s preparation to. it is possible to use Bettkher's camera, in a cut this defect is eliminated. The glass ring 10 mm high is attached to a usual slide plate by means of wax or paraffin. The upper edge of a ring is greased with vaseline and on it cover glass with the studied culture is imposed (a drop down). On a bottom of the camera for maintenance of the corresponding humidity previously place a drop of water. The similar camera can be mounted also on a special slide plate with a deep ring groove, to-ruyu fill with water. Mikroskopirovaniye of live objects in V. to. it is made by means of strong dry systems or immersion system. Force of lighting at the same time is regulated by narrowing of a diaphragm. In the beginning at small increase find edge of a drop, then, having moved it in a midfield of sight, change a lens. It is better to make observation in a dark field. For more detailed studying of morphology of microorganisms (is more often than protozoa) at the same time use their vital staining (see. Vital coloring ).

See also Bacteriological techniques , Microscopic methods of a research .

Bibliography: The guide to microbiological diagnosis of infectious diseases, under the editorship of K. I. Matveev, page 25, M., 1973; Epstein G. V. A workshop on parasitic protozoa and spirochetes, page 7, M. — L., 1940.

V. G. Petrovskaya.