RESUMO
We report on our experience in the experimental induction of Neural Tube Defects (NTD) in the foetal rat by maternal administration of retinoic acid. The teratogen diluted in olive oil was administered in a single intragastric dose (125 mg/kg body weight) to pregnant rats (n = 31) on the 10th day of gestation. Pure olive oil was given to control rats (n = 9). The foetuses were recovered by caesarian section on the 20th day and prepared for morphological investigation. We have studied 201 experimental and 82 control animals. There were NTD in 36.3% of experimental foetuses and none in the control ones. Sacral dysraphism was the most frequent defect but we also observed Arnold Chiari malformations and crowding of the bony limits by an enlarged neural axis. Other associated malformations found were: craneofacial (78.1%), caudal (80%), anorectal (31.4%), and limb defects (89.5%). This simple and inexpensive model may allow us to gain a better knowledge of the biology in the foetus with NTD.