I Effect of Hydrocortisone on Radioautographic Grain Counts in Rat and Mouse Hepatic Cells Nucleus

Work on radioautographic localization of RNA synthesis has been reviewed by Prescott (1). The findings with this method show good correspondence with biochemical evidence by indicating the nucleus as the presumptive site of RNA synthesis, and the probability of transport of RNA from the nucleus to the cytoplasm has been established. The method has been applied by Nossal et al. (2) in semiquantitative studies related to RNA synthesis. The effect of the hormone aldosterone on RNA synthesis has been studied radioautographically in toad bladder tissue (3). An increase of uridine incorporation as a result of the hormone action was observed. Biochemical evidence has indicated a selective alteration of hepatic messenger RNA synthesis resulting from the action of several hormones, among them hydrocortisone (4). It seemed desirable to use radioautography to look for a morphological expression of the events described by Kidson and Kirby (4). Thus, the events of RNA synthesis could be studied in situ with the light microscope, and radioautographs