Microangiographic Studies of Kidney and Brain in Animals: Technical Aspects †

The application of X-rays to microscopic study of thin specimens was first attempted by Heycock and Neville' in 1897, two years after the discovery of X-rays. This was followed in 1913 by Goby's' demonstration of microscopic details of small biological samples by radiographing the thin specimen in close contact with a photographic plate. The negative was subsequently enlarged photographically. He introduced the term, microradiography, and in 1925 succeed in producing stereomicroradiographs.' In recent years, microradiography has progressed along two lines: the quantitative analysis of cell mass and of cellular molecular constituents, and the qualitative investigation of morphology, pathology, and physiology of biological systems, especially with the aid of radiopaque contrast media. As early as 1935, Grechishkin and Prives' in Leningrad attempted to visualize small blood vessels in bone with microradiographic technique, using Thorotrastt as a contrast medium. They were unable to define vessels of capillary size because of the coarse-grained emulsion they used. Bohatyrschuk' in Kiev in 1944, using a fine-grained emulsion and a Bucky X-ray tube, demonstrated capillaries with Thorotrast in sections of mammalian organs and tumors. The British school under Barclay1" in 1947-1949 used a sealed-off diffraction X-ray tube and a variety of contrast media including Thorotrast, colloidal silver iodide, colloidal metallic bismuth, and Neoprine Laxtexif in the study of minute vessels in surgical and autopsy specimens. In this country, Tirman and associates" produced technically good micro-