of Human Bone Marrow after Accidental Exposure to Ionizing Radiation
461
B
dD
Fig. 3. Abnormalities in autoradiographs of bone marrow smears ofrats after total bodyirra-
diation and injection of H3 thymidine. A: Abnormal anaphase, 18 hours after 1500 r. Chromo-
somal bridges and fragments. B: Abnormal telophase, 18 hours after 550 r. with chromosomal
bridges and lost chromosomesand fragmentation. C: Binucleated myelocyte with chromosomal
bridge in DNA synthesis, 18 hours after 550 r. D: Fragmented nucleus in DNA synthesis,
24 hours after 1000 r.
chromatin clump, whereas the other chromosomes are more clearly outlined. In
anaphases, chromosomalstickiness caused formation of chromosomal bridges
which were observed frequently. These bridges consisted of 1, 2 or more chromosomes, sometimes they were almost as broad as the nucleusitself (Fig. 2), suggesting “‘amitotic’”’ divisions, when recognized in the interphase cells.
Chromosomal fragmentation was easy to recognize in anaphases and telophases
of erythroid and myeloid precursors (Fig. 2). One chromosomal fragment re-