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Examining data describing the sex composition of 1074 Caesarean-delivered litters of house mice, 253 Caesarean-delivered and 265 vaginally delivered litters of Mongolian gerbils, and 854 vaginally delivered litters of golden hamsters, we determined whether segregation of sexes between uterine horns and correlations between litter size and litter sex ratio were present in each of the three rodent species studied. Although significant deviations from expected distributions of male and female fetuses were found, these deviations from chance were not the same in any two of the three species examined. Analyses also indicated that the correlation between litter size and litter sex ratio that Huck, Seger, and Lisk (1990) found in vaginally delivered infant hamsters is present in vaginally delivered infant Mongolian gerbils, but not in their Caesarean-delivered colony mates. In gerbils, and perhaps hamsters as well, the correlation between litter size and litter sex ratio appears to be a result of sex-biased perinatal mortality correlated with litter size rather than of sex-biased conception correlated with litter size
Behavior. --- Birth. --- Colonies. --- Female mongolian gerbils. --- Female. --- Fetuses. --- Gerbil. --- Gerbils. --- Golden hamster. --- Golden-hamster. --- Golden-hamsters. --- Hamster. --- Hamsters. --- Horns. --- House mice. --- Infant. --- Litter sex ratio. --- Litter size. --- Male. --- Meriones-unguiculatus. --- Mice. --- Mongolian gerbil. --- Mongolian gerbils. --- Mongolian-gerbil. --- Mortality. --- Mouse. --- Perinatal. --- Rodent. --- Sex ratio. --- Sex. --- Sexes. --- Size. --- Time. --- Uterine position.
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Following either a) castration or b) both castration and implantation with capsules releasing a constant, physiological dose of testosterone, adult male Mongolian gerbils that had matured in intrauterine positions between two male fetuses still scent marked with greater frequency than did male gerbils that had matured in intrauterine positions between two female fetuses. We also found significant positive correlations between the relative frequency of scent marking exhibited by individual male gerbils when intact, after castration and after both castration and implantation with capsules releasing testosterone. Each of these findings is consistent with the view that differential exposure to testosterone, as a consequence of fetal intrauterine position, has lasting effects on the organization of scent-marking by male gerbils
Adult. --- Castration. --- Exposure. --- Female. --- Fetuses. --- Frequency. --- Gerbil. --- Gerbils. --- Implantation. --- Intrauterine position. --- Intrauterine positions. --- Male mongolian gerbils. --- Male. --- Marking. --- Mongolian gerbil. --- Mongolian gerbils. --- Mongolian-gerbil. --- Organization. --- Physiological. --- Position. --- Positions. --- Scent marking. --- Scent-marking. --- Scent. --- Territorial marking. --- Testosterone. --- Time. --- Uterine position.
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