MOUSE IMMATURE OOCYTES IRRADIATED IN-VIVO AT 14-DAYS OF AGE AND EVALUATED FOR TRANSMITTED EFFECTS USING THE AGGREGATION EMBRYO CHIMERA ASSAY

A previous study using the mouse-preimplantation-embryo-chimera assay demonstrated a reproducible transmitted effect (proliferation disadvan tage observed in early embryos) from females irradiated as 49-day-old adults using 0.15 Gy of gammma rays and then mated seven weeks later, i.e., embryos were from oocytes that were immature at time of irradiat ion. Because mouse immature oocytes are known to be much more radiosen sitive to cell killing in juveniles than in adults, a follow-on study was performed here using 14-day-old juvenile mice. In contrast to adul ts, the exposure of juveniles to 0.15 Gy of gamma rays did not result in a detectable transmitted proliferation disadvantage when animals we re mated 7 or 12 weeks later. This observation is discussed in light o f previous studies on mouse immature oocytes and embryo chimeras.