Teratogenesis: insights from animal models

Teratogenesis is the process by which birth defects or differences arise in an embryo or foetus by external agents. Birth differences may include both structural malformations and functional impairments, such as intellectual disabilities. Teratology is the study of the causes and underlying mechanisms leading to these birth differences. A teratogen is a substance (from outside the body) that causes birth differences or malformations. Examples of teratogens include medicinal drugs, such as thalidomide; environmental toxins, for example cadmium as well as environmental pollutants, including pesticides and endocrine-disrupting compounds. Other causes of teratogenesis include viruses, for example rubella and Zika virus; physical compression in utero and poor diet. Animal models are used to study the mechanisms by which teratogens result in birth differences or malformations, and these studies can also give insights into normal development. The study and understanding of teratogenesis is also essential for making safer and more targeted therapeutic drugs.