RENAL DISTRIBUTION OF ¹⁰⁹Cd BY LIGHT AND ELECTRONMICROSCOPIC AUTORADIOGRAPHIES

Abstract

In using an improved fixation, light and electronmicroscopic autoradiography were done on the mouse kidney after 5 hr of intraperitoneal injection of 200μCi of ¹⁰⁹CdCl₂. The kidney incorporated 5.1% of the administered radiocadmium. The radiocadmium was evidently higher in the cortex than in the medulla and increased from the juxtamedullary zone to the capsular surface in cortex. There was a wide variety of grain density among proximal tubules, which were always higher as compared with distal tubules, glomeruli, blood vessels and connective tissue. Electronmicroscopic autoradiography gave also almost the same results. As those findings were in rather good agreement with the hitherto reported results on the frozen-dried section, it was suggested that the improved fixation could be useful alternative of the latter method. It was also interesting to note that the highest "relative density", when expressed as grain numbers per unit area of an organella, was obtained in the basement membrane of the proximal and distal tubules.