Localization of plutonium-241 in the testis. An interspecies comparison using light and electron microscope autoradiography.

The distribution and localization of 241Pu in the testes of rats, guinea-pigs and a dog were determined using light and electron microscope autoradiography. These species were used because of the variation in the morphology and ultrastructure exhibited in their testicular tissues. In all animals the 241Pu was localized in testicular interstitial tissue and little was evident in the seminiferous tubules. There were marked species differences in the percentage of interstitial tissue cells labelled with 241Pu; 18 per cent of the cells labelled in rats, 9 per cent in guinea-pigs and 6 per cent in the dog. Electron microscope autoradiography demonstrates that 241Pu is localized in macrophages of the interstitial tissue in all species and appears to be concentrated in the lysosomal system of the cell. Based on differences in the histology and microstructure of testicular interstitial tissues and the patterns of 241Pu incorporation in these species, implications for predicting plutonium localization in human tissue are discussed.