ABSTRACT
Approximately 3" of human new-borns present with congenital malformations. Due to the development of prenatal diagnostic procedures, advanced surgical techniques, and intensive postoperative care, most infants with otherwise fatal malformations can be rescued by an operation in the neonatal period. Identification of teratogens helps to reduce the incidence of malformations when exposure can be avoided, and pathogenetic studies might aid in designing therapeutic measures. Both treatment and prevention critically depend on basic embryological research. Approximately 20" of congenital malformations are of genetic origin. Most surgically correctable malformations are associated with chromosomal disorders, trisomy 21, 13, or 18, or are of multifactorial inheritance with a small risk of recurrence. Over the last two decades, a number of animal models were developed with the potential to gain a better understanding of the morphology of not only malformed but also normal embryos. These animal models can be divided into four subgroups, such as, surgical models, chemical models, genetic models, and viral models.
