Early ultrastructural lesions induced in bone marrow cells by 241-americium

The modifications described here, condensation of nuclear material, compaction of cytoplasm and cytoplasmic fragmentation with organelles preservation, show all the criteria of apoptosis, a mode of cell death, first described by Kerr. Observed cellular fragmentation, correspond to apoptosis body formation of a phase of apoptosis. Apoptotic bodies produced in tissue are generally phagocyted by surrounding cells, as observed in this study. These lesions are similar to those induced by external irradiation of acute exposure to 2 and 6 Gy doses of 137Cesium (Ghassah, personal communication), but different of those produced by 239Plutonium administration at the same dose. Finally, these ultrastructural observations show an evidence of apoptosis. (authors)