Congenital defects have long been considered as bizarre curiosities only deserving display in anatomical museums. Persons surviving with gross malformations were put away in the wards of institutions, and even some of these people tried to make a living by exhibiting themselves at fairs. However, in the last decades several medical disciplines gradually became interested in the problems of patients with congenital disorders. Genetics discovered the chromosomal bases of some syndromes, surgery and pediatrics developed techniques for the treatment of several anomalies, obstetrics reduced the incidence of perinatal brain damage, and even prenatal diagnostic tests became available.

Embryology contributed descriptions and analyses of prenatal development, and the investigators tried to correlate the morphology of birth defects with the developmental processes that had been discovered. However, definitive conclusions were difficult to make. The finding that congenital malformations can be produced in mammals by various exogenous agents opened a new area of research. This experimental teratology concentrated on the morphogenesis of defects, interaction of exogenous agents with developmental processes, and problems of drug safety in pregnancy. It was found that vitamin A is teratogenic when administered in high doses, and in almost all organ systems malformations were produced by this substance. The reports published on this subject not only present the data on one of the most investigated teratogens, but also illustrate the evolution of experimental teratology in the past years. Therefore, we decided to present a review of these publications. To present a systematic and conveniently arranged survey, the malformations recorded in the literature are arranged by organ system. Cleft palate is dealt with separately, and some chapters are devoted to the pathophysiological aspects of vitamin A teratogenesis.