Printed in Brazil DENTAL GERM FORMATION AS INFLUENCED BY 5-FLUOROURACIL (5-FU) IN NEWBORN RATS

It was studied the influence of the antimitotic drug 5 fluorouracil (5-FU), administered to pregnant rats, on dental germ formation of newborn rats. A total of 125 female aged 90-100 days and 15 male adult rats (Rattus rattus norvaegicus, albinus, Wistar) were used. The drug was injected intraperitoneally in single doses to females at the 9, 10, 11, 12 and 13 days of pregnancy. The animals were divided in four groups according to the doses administered: 10, 20, 30 and 40 mg/kg. Results show that the drug induced no toxicity to mothers, other than loss of body weight with higher doses (30-40 mg/kg), but caused in the fetuses dental germ anomalies and body external malformations. The proportion of such anomalies were, besides dose dependent, influenced by the day of pregnancy when the drug was administered to the mothers: there was a greater sensitivity at the 9 day and a lesser one at the 10 day. Higher doses (30-40 mg/kg) caused frequently embryonic death or fetal uterine reabsorption. Agenesia of the dental germ was frequently found.