A Photoelectric Microdensitometer

Abstract

The apparatus is developed to obtain an objective estimate of the intensity of the reaction to colorigenic histochemical tests such as the Feulgen test. The assembly consists of a Leitz Makam camera fitted with a ground glass screen and mounted on a monocular microscope supplied with illumination of the Kohler type. A model 512 Photovolt Electronic Photometer with a Type C search unit is mounted in a rack and pinion transversing mechanism so mounted as to move the search unit over the ground glass screen. In practice a filter of color complementary to the color to be studied is used. The light intensity is adjusted so that the meter reads 100 when search unit is over a clear area on slide; the section to be studied is moved into the field and meter readings obtained in various parts of image are read as % transmission.