Radioautography of tritiated sex steroids in the rat

Summary Four radioautographic methods for soluble substances were compared to each other. When using the wire-loop method of Miller et al. (1964) difficulties were met because detachment of emulsion from the object slide. Severe chemographic artifacts in the radioautograms hampered the results when using the method of Appleton (1964). The freeze-drying and paraffin embedding method of Hammarström et al. (1965) resulted an extensive diffusion of radioactivity. Therefore, a simple dry-fixation method for steroid radioautography was developed.Among the female hypothalamic nuclei the preoptic area, the anterior hypothalamic area, the nucleus ventromedialis, paraventricularis and arcuatus showed the highest labelling index after injection of tritiated estradiol intravenously. In addition, high labelling index was seen in the hippocampus. Almost all radioactivity was seen in the nuclei of the neurons. Radioactivity in the uterus was localized in the nuclei of the epithelial and stromal cells. Estradiol in the male rats localized in the nucleus paraventricularis, ventromedialis, dorsomedialis and amygdalae. Only very few of the prostatic cells were labelled.Tritiated testosterone was localized in both sexes in the hippocampus, in the nucleus arcuatus and ventromedialis. Some radioactivity was seen in the anterior hypothalmic area. The nuclei of the epithelial and stromal cells in the accessory sex organs (ventral prostate, seminal vesicle, epididymis) concentrated radioactivity very effectively.Tritiated dihydrotestosterone was localized in the epithelial and stromal cells of male accessory sex glands as testosterone.