ABSTRACT
The developing nervous system of the embryo, fetus, and child is a vulnerable target of many neurotoxic agents. Abnormal embryogenesis is initiated by defect-causing agents, or teratogens, acting on the developing tissues and cells. It was generally thought that teratological defects are “agent specific, that each agent has the capacity of producing specific defects. Teratology is the study of the abnormal development of the embryo, fetus, and child. A teratogen is any chemical substance or physical condition that can produce such abnormalities. The abnormal development might be expressed—in decreasing order of severity—by death, malformation, growth retardation, and functional disorder. Environmental teratogens can reach the developing tissue in several ways: directly, via the placenta, in the perinatal period of development through breast feeding, and as a result of the infant’s own ingestion. The vast literature on neuroteratology is sharply divided into animal and human studies; animal research is frequently divided into research on subhuman primates and lower species.
