with respect to the sex of irradiated animals (mice, CFW strain, 40-50 or 1h0-
150 days of age) in the interval of daily dosage between 2 and 256 R/day of 400
kV x rays.
250.
In the series by Kohn and Guttman [K6] (see also paragraphs 263-264) the
animal's sex was shown to be an important factor for life-span-shortening in
CAF1 mice.
During much of the adult life the female animals reacted to doses
below 250 rad, although the slope of the female dose-effect relationship between 250 and 400 rad was less than that of the males.
became less sensitive than the males.
Late in life the females
Here again, changes in the endocrine ba-
lance were reputed to be at the origin of such phenomena, in the sense that the
female's changes in sensitivity might be a manifestation of the increase and
fall of ovarian endocrine function.
Such a hypothesis would be in accordance
with the fact that continuous low-level treatment with estrogen hormone increased the age-specific mortality rate of the Balb/c female mouse after x-irradiation [K13].
It is of interest that in the CAF1 strain the reduction of
life-span was not correlated with the induction of ovarian tumours, which were
actually depressed and not enhanced at the doses used.
251.
Sacher and Grahn [S4] showed that LAF1 female mice after life-time ir-
radiation were slightly more sensitive than males in the 5-10 days period of
survival but became consistently more sensitive in the 17-40 day period.
In
the mice surviving during the periods of 10-15 and of 40-130 days the difference
between sexes was either much smaller or non-existent; at survival times in excess of 130 days females accumulated consistently higher doses than males. In
the large experiments of Upton, Randolph and Conklin [U7] on RF/Un mice no
obvious effect of sex can be traced from the data.
Protraction factors in male
animals irradiated with gamma rays at low dose rates appeared to be in the same
direction as in female animals but considerably more pronounced.
Consequently,
RBE data were different in the two sexes.
252.
Sex differences in A/J strain in regard to radiation-induced life-shor-
tening (x rays, single exposures, 150 - 600 R) were also seen by Storer [S30].
At exposures of 600 R the female animals lost nearly four times as many days of
life as did the male mice.
Qualitatively similar results in male and female
mice were observed in the experiments of Ainsworth et al.
[A7] and the apparent
quantitative differences in response after single and fractionated gamma-ray