478 .
FLIEDNER, ANDREWS, CRONKITE AND BOND
Fig. 4.—“Mitotically connected abnormalities” in bone marrow smears 3.5 years
after exposure to 236-365 rads. A: Myelocyte mitosis with aberrant chromosomes;
B: myelocyte mitosis with chromosomal bridge; C: tripolar mitosis in early red cell
precursor; D-F: binucleated erythroblast at the proerythroblast, macroblast and
basophilic normoblast maturation stage.
.
difference between the means of the high dose group persons and the normals
is statistically significant (0.01 > p > 0.001), while p for the “low dose”
group is 0.05.* Thus, the latter findings are not significant but suggestive. Not
quantitatively evaluated was the apparent increase in red cell precursors
with cytoplasmic bridges between cells with clear-cut interphase nuclei in the
high dose group as compared to the normal smears. This abnormality has been
described by E. Schwarz*° who considered it to represent “residual interzonal
fibers.”
In a separate approach, bi- or multinucleated erythroblasts were recorded
in the course of counting 100 mitoses of all cell types in marrow smears of
the exposed individuals and of normal persons. It was found that the means
of the frequency of such atypical erythroblasts in the high dose group were
7.4 and 3.3 per 100 mitoses in the low dose group. In smears of normal persons, a total of 161 mitoses were counted in the same way and 1.8 atypical
erythroblasts were found per 100 mitoses. Binucleated cells of the myelocytic
series occurred at a frequency of 2.5 per 100 mitoses of all types in the normal
marrow smears, comparedto 2.2 in the high dose group and 1 in the low dose
*Berman’s controls’? have a higher incidence of binucleated cells than ours, Since our
controls and irradiated subjects were studied in exactly the same manner, we have chosen
to make thestatistical comparison with our controls rather than Berman’s normal values.