planimetry in histology

From Big Medical Encyclopedia

PLANIMETRY in histology (Latin planum a surface, the plane + grech, metreo to measure, measure) — a method of determination of the area of microobjects by means of the planimeter. The planimeter (fig.) consists of the bypass lever (1) supplied with a bypass edge or a magnifying glass with a bypass point (2) and the metering device (3), the polar lever (4) with the polar weight (5) which not movably is fixed by an edge of a needle in the plane of the image. Accuracy of indications of the planimeter (an error of a method) fluctuates from 0,2 to 1% of the measured area.

Planimeter: 1 — bypass the lever, 2 — a bypass point, 3 — the adjuster of scale on the bypass lever, 4 — the polar lever, 5 — the polar weight, 6 — the metering device, 7 — the nonius of a measuring drum with divisions of the first order, 8 — a measuring drum with divisions of the second and third order, 9 — a horizontal disk with divisions of the fourth order, 10 — the measured object (the arrow specified the direction of the movement of a bypass point).

For P. microdrug is photographed or receive its image on paper by means of a projective microscope, the drawing device, the set-top box, etc., then contours of the measured object lead round. The received drawing is strengthened on a plain surface. The adjuster of scale on the bypass lever (3) is installed at the smallest size convenient for work with objects of this experiment series. Any point of the measured figure (10) is marked, establish over it a bypass point (an edge, 2) and note the initial position of a measuring drum by means of the metering device (6). Then the bypass point (edge) is moved clockwise, strictly adhering to contours of a figure. At the moment when the bypass edge returns to an initial point of a figure, note provision of a measuring drum again. The difference in indications of the metering device (7 — 9) of a drum in the end and at the beginning of measurement is also the area of a figure in conventional planimetric units. For transfer of these units in square micro or nanometers on paper postpone the line which length on the scale of a microscope corresponds, e.g., 10 microns (nanometer); on this line build a square, measure its area the planimeter and calculate value of conventional planimetric unit.

Kaspersson (T. Caspersson) and sotr. (1953, 1969) the design of the microplanimeter — the device allowing to make P. directly under a microscope is developed, passing a stage of an intermediate sketch or photography of an object.

The newest systems of the analysis of microobjects allow to determine at the same time the area, volume, optical density and some other parameters with automatic or semi-automatic data recording (see. Cytophotometry ).

Bibliography: L. S.'s agroskin and G. V's Pa-payan. Cytophotometry, page 157, etc., L., 1977; Hesin Ya. E, Sizes of kernels and functional condition of cells, page 15, M., 1967.

Ya. E. Hesinonim