RESUMEN
For the study on the teratogenic effects and its mechanism of FUDR on the developing rat fetuses, Sprague -Dawley rats as experimental animal and 5 -fluoro -2 '-deoxyuridine (Sigma chemicals) as FUDR were used respectively. On the day of gestation 10.5, 60 mg/kg, 65 mg/kg and 70 mg/kg of FUDR was injected intraperitoneally, and sacrificed under ether anesthesia on the day of gestation 17.5. External congenital malformations such as hydrocephalus, lens defect, cleft palate, short tail, forelimb and hindlimb malformations were observed under stereoscope, and compared each other with control group. The results were as follows; 1. Congenital anomalies induced by FUDR were hydrocephalus, lens defect, cleft palate, short tail, and defects of extremities such as phocomelia, loss of first and second digits, undergrowth of digits, and syndactyly. 2. There is close relation between the rate of occurance of congenital anomalies and doses of FUDR in some organs. 3. There is significant differences between forelimbs and hindlimbs and between right forelimb and left forelimb in the rate of occurance of congenital anomalies of the extremities. According to the above results, it is considered that there is significant differences between the types and occurance rates of congenital anomalies induced by FUDR and the doses of FUDR. But distinct mechanism of action during teratogenesis of FUDR still remains unclear.