1978 Volume 18 Issue 4 Pages 227-233
When bredinin was intraperitoneally injected into pregnant rats on day 11 at 2.5, 5.0, 7.5 and 10.0 mg/kg, fetal mortality was 5.1%, 42.1%, 95.5% and 100%, respectively. Fetal abnormalities were induced in relation to the amount of the administered drug. Next, for the examination of the stage specificity, a dose of 5 mg/kg was administered on various day during the organogenetic period. The drug administration on day 7, 8, 10 or 11 of gestation resulted in a high fetal mortality, while the administration on day 9 caused a relatively low fetal mortality. This result demonstrated that there were two susceptible periods in rat embryonic development to the lethal action of bredinin. There was a close relationship between types of abnormalities and the day of administration : fetuses of rats treated on day 9 of gestation showed a relatively low percentage of skeletal abnormalities and a high percentage of visceral abnormalities. However, in fetuses of those treated on day 8 or 10 of gestation, skeletal abnormalities were marked and visceral abnormalities were relatively scarce.
