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FLIEDNER, ANDREWS, CRONKITE AND BOND
Fig. 1.—‘“Mitotically connected abnormalities” in erythropoietic precursors
of
human bone marrow during the first days after exposure. Chromosomal bridge: A,
B, C; internuclear bridge: H; aberrant chromosomes in mitoses or karyomeres in
interphase cells: C-N; incomplete nuclear division (P?): O; “giant” oxyphilic normoblast: P.
J, M). In mitotic figures, they were found between the two poles in anaphase,
or “left behind” in the cytoplasm (fig. 1, D, E, G). Not enough mitotic figures
were counted in the “early” samples to give accurate values for the frequency
of obvious mitotic abnormalities (bridges in ana- and telophase, chromatin
fragments); but it was estimated that 20-50 per cent of mitoses were abnormal
in the 12-hour and 2-day smears of the “high dose” group.
The smears of the low dose group were available only from days 4 and
10. The frequency of erythroblasts with karyomeres on day 4 was lower than
in the high dose group but slightly elevated compared to normal, suggesting
a dose dependency (fig. 3).