Long-term effects on offspring of exposure of oocytes and embryos to chemical and physical agents

Central to this review is the knowledge that, in some livestock species, th e environment in which fertilization and embryo development occurs influenc es not only preimplantation embryo development but also the phenotype of re sulting offspring. This knowledge is based on in-vitro studies where the in duced changes in the embryo can result in an array of developmental abnorma lities after transfer including fetal overgrowth. Whilst such findings are of immediate relevance to assisted reproduction in the human, they also rai se another equally important but less obvious issue, Can the in-vivo enviro nments in which fertilization and embryo development normally occur be infl uenced by exogenous factors (either physical or chemical) in such a way tha t long-term development is adversely affected? In a global environment of i ncreased use of synthetic chemicals and increased production of pollutants, it is an issue of growing relevance. This review examines technical inform ation that is pertinent to these issues together with a brief assessment of some possible molecular mechanisms responsible for aberrant development. T he review concludes with an assessment of the clinical significance of the findings.