RESUMEN
Bone and other malformations caused by the ingestion of Mimosa tenuiflora are common in ruminants in the Brazilian semiarid. The aim of this research was to study the teratogenic effects of M. tenuiflora in Wistar rats (Rattus novergicus). The experimental group had 15 females and was fed, from the 6th to the 21st day of pregnancy, with a ration containing 10% of M. tenuiflora seeds. The control group, with 10 females, was fed with the same ration without seeds. There were no differences in weight gains, and food and water consumption between treated and control rats. Ninety bone malformations were observed in 40 of the 101 fetuses born in the experimental group, and four malformations were observed in three of the 58 fetuses born in the control group (p<0.05). The weight and number of ossification centers of the fetuses from the experimental group were higher than those from the control group (p<0.05). It is concluded that the seeds of M. tenuiflora are teratogenic to rat fetuses.