New animal model for the study of neural tube defects.

The induction of spina bifida in rhesus monkeys by treating the pregnant females with the anticonvulsant drug, valproic acid (VPA), during the early stage of gestation which coincides with the critical period of neural tube fusion is discussed. It was found that both the dosage and timing of VPA administration were crucial in the development of lesions which are similar to human spina bifida aperta. The teratogenic protocols and the gross and hystologic characterization of the induced lesions are presented and the epidemiological findings are discussed.