Abstract
Lucerne (Medicago sativa L.) in which the proteins were labelled with radioactive selenium was fed to mice. The distribution of 75Se among the various organs was studied. On the basis of 75Se activity per unit wet weight, the importance of the liver and kidney as metabolic sites is confirmed, and attention is directed to the pancreas, endocrines, and the stomach wall as additional sites where selenium is present in comparable concentrations. The relative importance of the above organs is supported by the results of autoradiography; in addition, this demonstrates the high concentration of 75Se in the cell nuclei, where selenium may play a fundamental role. Radioactive selenium from labelled lucerne was found in the milk of a lactating mouse within 4 hr of it being fed. Within 24 hr approximately 20% of the selenium absorbed by the dam had been transferred to the young mice through the milk.