title: Further studies on effects of X-irradiation on prespermatid stages of the Northern vole Microtus oeconomus: low induction of sex-chromosomal nondisjunction and very high induction of diploid spermatids.
abstract: Microtus males have been irradiated with X-ray doses of 25, 50, 100 and 200 rad and early spermatids were then analyzed for evidence of induction of sex-chromosomal nondisjunction and diploid spermatids at 1, 4, 6, 7, 9 and 12 days after treatment. In contrast to earlier findings, there was no induction of nondisjunction above control levels. A possible explanation for the differences in results of old and new experiments might be that genetic changes have taken place in the Microtus colony that was initiated with animals trapped in the wild, but which has now become highly inbred. In the present experiment, diploid spermatids were frequently induced. The dose--effect relationships at the different time intervals were linear, but the slopes were different, indicating stage-specific differences in sensitivity. The average doubling dose is of the order of 12 rad with a range of 5-30 rad for the individual time intervals. When diploid spermatozoa in man are also inducible by such low doses of X-rays, the consequence would be an increase of triploid abortions which would constitute an undesirable form of personal or family hardship.
mesh_terms: D000818:Animals; D003411:Arvicolinae / Q000235:genetics*; D002869:Chromosome Aberrations; D004307:Dose-Response Relationship, Radiation; D008297:Male; D012377:Rodentia / Q000235:genetics*; D012730:Sex Chromosomes / Q000528:radiation effects*; D013087:Spermatids / Q000648:ultrastructure*; D013094:Spermatozoa / Q000648:ultrastructure*; D013997:Time Factors; D014965:X-Rays