480 ~
FLIEDNER, ANDREWS, CRONKITE AND BOND
Table 3.—Mitotic Indices 3.5 Years after the Exposure
(Feulgen-stained Squash Preparation)
Individuals
High dose group
A
B
Cc
D
E
Slides
Counted
Cells Counted
per Slide
5
5
5
5
5
1000
1000
1000
1000
1000
Range of Mitoses
per 1000 Cells
6-14
7-12
8-11
5-13
12-18
Mean
Low dose group
F
G
H
Comparisons*
Seven healthy
‘comparisons
5
5
5
38
1000
1000
1000
1000
Mean
x
Standard
Deviation
9.6
9.2
9.4
9.0
13.6
4.13
1.87
1,09
1.07
2.59
10.16
1.94
(p > 0.05
compared to normal)
6-11
3-12
6-14
8.8
7.4
8.6
1.92
3.5
3.12
Mean
8.27
0.59
2-18
8.97
1.0
*Data taken from Fliedneret al.: Acta. haemat. 22:65, 1959.
cent, metaphase 77.2 per cent, anaphase 5.9 per cent, and telephase 1.6 per
cent. In the low dose group, the respective values were: prophase 21 per
cent, metaphase 71 per cent, anaphase 6.5 per cent and telephase 2.5 per cent.
In bone marrow smears of the exposed men prepared 3.5 years after the
accident, 100 mitoses were counted on each individual and classified into
erythropoietic, myelopoietic, and others; the latter including all mitoses which
were not clearly erythropoietic or myelocytic as well as those that occurred
in megakaryocytes, plasma cells and unclassified cell types. These values
are given in table 4 and comparedto similar data previously obtained on normal persons.?® The data show that the distribution of mitoses is about the
same for the high dose, the low dose and the control group. It is obvious,
however, that a number of the mitotic figures seen in the high dose group,
and a smaller number in the low dose group were considered abnormal.
Mitoses considered abnormal in these preparations showed one or more
chromosomes or fragments obviously excluded from further karyokinesis
(aberrant chromosomes), or clearly visible single or multiple chromosome
bridges in late anaphase or telephase. In 138 mitoses counted in smears of
two “normal” controls, only two such abnormal mitoses with an aberrant
chromosome were seen. Since no particular search for these abnormalities was
made in the other contro] smears counted previously, it is not certain what
the exact frequency of such abnormal mitoses is in healthy persons.
DISCUSSION
The findings presented indicate that cytologic abnormalities were present
in the marrow after accidental whole body irradiation not only during the
first weeks after exposure but even 3.5 years later. These abnormalities oc-
IU 2228