Experimental spina bifida and associated malformations.

Seven litters and 17 near-term rats of mothers treated with teratogens during gestation were analyzed for concordance and discordance of congenital malformations of the central nervous system. In animals with spina bifida a firm association with Arnold-Chiari malformation was found but only in fetuses near term. Associations with aqueduct stenosis and hydrocephalus were poor. In general, the findings support the theory that the components of the spina bifida complex develop from a common teratogenic disturbance but independent from each other.