Reproductive function in mice exposed to neonatal irradiation

Abstract

Lifetime reproductive function following irradiation on the day of birth was studied in nine genotypes of mice obtained by crossing three inbred strains, BALB/Gw, K/Gw, and S/Gw, in all possible ways providing three inbred genotypes and six hybrid genotypes. The mice of each genotype were exposed to single whole-body 250 pkv X-ray dosages of 0R, 20R, 80R, 160R, and 320R. The experimental design gave an oppurtunity of relating radiation responses to the various genetic categories of offspring (inbreds versus hybrids, reciprocals, and so on). Mice were mated at 75 days of age to untreated mice of the Z/Gw strain. The incidence of sterility was increased appreciably only after exposures of 160R and above. Following 320R sterility was much higher in females than in males. The total number of litters and progeny also was affected adversely by neonatal irradiation. Females, in both cases, exhibited more severe effects than did the males. Compared to mice irradiated as 7 1 2 day old fetuses, neonatally-irradiated males females had decreased reproductive capacity and neonatally-irradiated males had increased reproductive capacity. No effects due to irradiation were noted in either the sex ratio of the progeny or the survival of progeny to 21 days of age. Heterosis due to strain crossing was observed in all measures of reproductive performance. Differential genotypic responses to neonatal irradiation were indicated by significant genotype x radiation interactions for reproductive responses.