Three mouse embryos, representative of the study, that describes how the teratogenic drug Valproic acid can cause neurodevelopmental birth defects in mice, including microcephaly and exencephaly. The embryo on the left is a normal embryo, with no exposure to Valproic acid. The embryo in the middle is smaller and has microcephaly, while the embryo on the right exhibits exencephaly. The middle embryo and the one on the right were both exposed to Valproic acid.