A Dose-Response Relationship between Chromosome Aberrations and Hypoxic Insults in Overripened Hamster Ova

Abstract

An attempt was made to analyze the quantitative occurrence of chromosome anomalies by the exposure of slightly overripened ova (delayed fertilization) to hypoxic insults in golden hamsters. Three groups were established: (1) a control group (Po₂ = 152 mmHg); (2) a 4,500 m altitude group (Po₂ = 87 mmHg); and (3) a 9,000 m altitude group (Po₂ = 46 mmHg). About 1.5 hr post-ovulatory aging revealed no striking effect on reproductive performance, as well as on the production of chromosome aberrations. Nevertheless, even in a slightly overripened condition ovum increased in susceptibility to the production of chromosome anomalies after hypoxic exposure equivalent to 4,500 m altitude. The dose-response relationship between hypoxia and the occurrence of triploidies was particularly distinguished. On the other hand, a similar relationship was not so evident in the production of aneuploidies, especially of trisomies. It can, therefore, be surmised that the change in the cytogenetic milieu at the time of the second polar body extrusion has some quantitative relation to the severity of environmental stressors.