5 per cent level than that of the males.
When only the mean survival times
between 30 per cent and 100 per cent mortality were considered in order to ex-
clude early mortality, this sex difference remained evident.
PUT.
Sex differences in Balb/c, A/Jax, A/He, C3Hf/He and C57BL/6 mice were
evident when data for female or for male animals of all strains were pooled together as a function of dose and fitted by linear regressions: the reduction of
mean after survival for a given dose increment was about twice in female than
in male animals [G10].
Ovarian disfunction resulting in ovarian tumour forma-
tion was suggested as the possible cause of this difference.
Grahn and Sacher
[G3] also showed a greater sensitivity of the females with respect to chronic
Life-shortening injury.
With x rays of three different energies the reduction
of life-span averaged in animals surviving the LD
female and 29 per cent in the male sex.
about 37 per cent in the
Female nies were uniformly more sensi-
tive than males when irradiated with gamma rays or fast neutrons
[U5].
This
was again attributed to the induction of tumours of the ovary or to hormonal
disturbances.
However, the RBE for neutrons against gamma rays was not signi-
ficantly different between the two sexes.
oe.
After single-dose irradiation of one hybrid and five inbred strains
of mice (200 kVp x rays, doses between 0.85 and 1.15 times the LD
differences within sex were not significant.
) strain
The two sexes had, aoever, sig-
nificantly different responses averaging for the males 0.28 days lost/R and for
the females 0.81 days/R (all strains pooled).
Difference tended to disappear
when corrections were introduced for animals dying of leukaemia and of ovarian
tumours.
Life-shortening in all strains after an acute treatment about the
150/30 seemed to be characterized by a single parameter applicable to all strains
and sexes and expressed as a constant number, 28 days of life lost/100 R.
Com-
bination of this primary injury term with other secondary parameters could pro-
vide equations predicting the final long-term effect for any combination of normal life expectancy, leukaemia incidence, ovarian tumour incidence and dose [G4].
2h9.
In the experiments of Lindop and Rotblat
[L1] the shapes of the survival
curves were similar for males and females SAS/ mice but showed small consistent
differences in favour of a higher resistance for males.
These differences were
not such, however, to warrant a separate analysis of the life-shortening effect
in the two sexes.
Moos
[M14]
also reported no difference in longevity response