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Biology of Reproduction, Vol 14, 478-480, Copyright © 1976 by Society for the Study of Reproduction
1 Department of Animal Science, Cornell University,
Ithaca, New York 14853 The Syrian hamsters differs from the rat in that the male has a longer average lifespan
than the female. The difference is highly significant statistically. Bred females have a shorter
lifespan than do unbred females but females exposed to vasectomized males, and thus
possible pseudopregnant, do not. Rats from a large sized, fast growing strain have
significantly longer average lifespans than do those of a smaller, slower growing strain; this is
in all categories except unbred and bred females in which the length of life is curtailed by
the high incidence of mammary and ovarian tumors in the fast growing strain. Females of
this strain exposed to the chance of pseudopregnancy di; not differ from unbred females in
their average lifespan. In the slower growing strain pregnancy shortened the average lifespan.
It follows that pregnancy in itself, not the persistence of corpora lutea, shortens the
lifespan.
Note:
ACKNOWLEDGMENTS
This work was supported in part by PHS Grant No.
5H01 HD01187. We wish to thank Mrs. Ruth Seither
for her work in caring for the animals and for carrying
out many of the breeding operations.
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