EFFECTS OF BLASTOCYST DEFICIENCIES INDUCED BY ASPIKIN TREATMENT DURING PREIMPLANTATION PERIOD IN RATS ON DEVELOPMENT OF EMBRYOS AFTER IMPLANTATION

Pregnant rats were treated orally with aspirin0.5 or 1.0g·kg^-1on d3(positivevaginal smear was considered as d 0)and were sacrificed on d 4.Some blastocysts collected on d 4were evaluated for gross morphology and cell number,and the remainings were transfered intopseudopregnant rats.Results showed that the rate of blastocysts with abnormal morphology were23.8%and 40.8%,respectively, in 0.5 and 1.0g·kg^-1of aspirin.These were significantly higherthan 6.8%of the control group. The cell number of blastocysts also decreased in the aspirin groups.The rate of implantation and live fetuses in the case of blastocysts with normal morphology wererelated negatively with the aspirin doses,espesially in the group of 1.0g· kg^-1of aspirin,theimplantation rate was significantly lower(38.6%).However,the implantation rate of blastocystswith abnormal morphology in both groups of aspirin were much less than that of the control group,and all embryos after implantation were resorped.No significant malformations were observed in thelive fetuses.These results suggest that the effects of blastocyst deficiencies induced by aspirin ondevelopment of embryos transfered into pseudopregnant rats mainly caused death of embryos,but notm3lformation offetuses.