title: Chromosome aberrations induced by tritiated water or 60Co gamma-rays at early pronuclear stage in mouse eggs.
abstract: The induction of chromosome aberrations in mouse eggs by exposure to HTO beta-particles and 60Co gamma-rays at the early pronuclear stage was examined at the first-cleavage metaphase by using an in vitro fertilization technique. Eggs at the pronuclear stage were exposed to beta-particles in a chemically defined medium containing tritiated water (HTO) for 2 h at 3-5 h after insemination. Other eggs at the same stage were exposed to gamma-rays from 60Co during the same period. The dose-response relationships for frequencies of chromosome aberrations per egg were fitted to a linear-quadratic model for HTO beta-particles, and to a linear model for 60Co gamma-rays. The chromosome aberrations were mainly chromosome-type, and the majority of all aberrations were fragments. RBE values of HTO beta-particles relative to 60Co gamma-rays and acute X-rays, which were estimated from the ratio of the linear regression coefficients over 0.05-Gy range, were 2.0 and 1.6, respectively.
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000528:radiation effects* / Q000648:ultrastructure; D002869:Chromosome Aberrations / Q000528:radiation effects*; D003037:Cobalt Radioisotopes; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005720:Gamma Rays; D008297:Male; D008677:Metaphase / Q000528:radiation effects; D051379:Mice; D011836:Radiation Tolerance; D014316:Tritium; D015053:Zygote / Q000528:radiation effects / Q000648:ultrastructure
chemical_list: D003037:Cobalt Radioisotopes; D014316:Tritium