EFFECTS OF WHOLE BODY IRRADIATION ON MARROW
477
Table 1.—Mitosis Early after the Accident as Seen in Wright's Stained Smears
12 Hours
2 Days
6-17-58
Individuals
Day 4 or 5
6-18-58
Mitoses
6-20 or 6-21-58
Mitoses
Mitoses
No. counted
per.1000
No. counted
per 1000
No. counted
per 1000
A
B
3000
2000
5
8.5
2000
2060
6.5
8
2000
2000
I
9
C
D
E
2000
2000
2000
3
3
2.5
2000
2000
2000
3.5
5
45
2000
2000
]
2.5
2000
2000
2000
5
4
5.5
High dose group
Low dose group
.
.F
G
H
Normal
(smears: Japa3!)
5
In an attempt to establish whether or not a determination of the mitotic
index is meaningful in marrow smears early after exposure, 2000 cells were
counted in each marrow smearof the high dose group at 12. hours, 2 days and
4 or 5 days, and in the low dose group on day 4 after exposure. The values
are given in table 1. The mitotic indices thus determined were in the range
of normal.?! As has been pointed out before,** mitotic index determinations
performed on ordinarily prepared marrow smears are not accurate and should
only be based on at least 5000 cells counted in squash preparations.
B. Manifestations of Radiation Injury “Late” after Exposure
Three and one-half years after the accidental whole-body exposure, the bone
marrow was reexamined in all eight persons. In this report, results of the
following studies were included: (1) Determination of the frequency of M.
C. Abn. using identical criteria as for the studies early after exposure, (2)
determination of the mitotic indices of the marrow; (3) determination of the
relative frequency of mitoses of differentcell lineages.
In marrow smears, a total of 15,000 erythroblasts were counted in the
high dose group and 7000 in the low dose group. The results were compared
to 10,000 erythroblasts counted in smears of healthy persons used as com-
parison. In the smears of the irradiated persons, a variety of cytologic abnormalities was observed which are rare in normal smears. Most striking was
the increased number of binucleated and the presence of a very few tri-
nucleated erythroblasts. Examples are shown in figure 4. In addition, an increased number of erythroblasts with karyomeres was found. In mitoses,
usually of the myelocytic series, chromosomes or fragments were found in
the cytoplasm, apparently excluded from further karyokinesis (fig. 4). In two
instances, tripolar mitoses were seen (fig. 4). In table 2, the frequency of
binucleated red cell precursors per 1000 erythroblasts is shown. In the high
dose group, the mean is 5.08 compared to 2.25 in two individuals of the low
dose group receiving about 70 rad, and to 1.2 in the comparison group. The