AbstractsBiology & Animal Science

The relationship between x-ray induced chromosome aberrations and x-ray induced embryonic abnormalities was studied. Golden hamsters were irradiated during four stages of gestation: the blastocyst stage, 4.5 days post-copulation; the primitive streak stage, 6.5 days post-copulation; the organogenesis stage, 9.5 days post-copulation; and the period of fetal growth, 11.5 days post-copulation. The incidence of induced embryonic abnormalities as a consequence of irradiation in these various stages was 26 percent, 100 percent, 88 percent, and 0 percent respectively. Irradiation during the primitive streak stage produced the greatest variety of teratisms. The number of induced chromosome aberrations was found to remain constant, regardless of the stage in which irradiation occurred. Thirty-six percent of the cells contained some sort of chromosome aberration six hours post-irradiation, however, the number of aberrations was only seventeen percent three days post-irradiation. It was concluded that irradiation causes chromosome aberrations, which in turn, may be responsible for cellular death. Cellular death causes the development of embryonic abnormalities if it occurs at a particularly critical stage of development. Therefore the chromosome aberrations are indirectly responsible for the embryonic abnormalities but there is no correlation between the numbers of chromosome aberrations and the numbers and types of embryonic abnormalities.