Developmental consequences of embryo and cell manipulation in mice and farm animals

Advances in biotechnology in recent decades have revolutionized our underst anding of early mammalian development and promise to provide ever more fine ly tuned and precisely targeted techniques for genetic enhancement of domes tic animal species. In demonstrating what is both technically and biologica lly possible, not only in mice but also in larger animal species, research has provided hope that previously intractable diseases and genetic defects can be successfully combated. Crucial to this research is the ability to cu lture oocytes, embryos and somatic cells in vitro and to sustain their deve lopment without inducing adverse short- or long-term consequences. There is a need to refine current culture strategies in farm animal species to avoi d jeopardizing their dependent technologies. A key to resolving current lim itations of culture strategies is to identify, acknowledge and then address those features of in vitro culture that compromise early regulation of mam malian development. The aim of this review is to appraise critically in vit ro embryo and somatic cell production strategies in the context of their im pact on developmental competence and normality at embryonic, fetal and late r stages. In addition, effects of physically manipulating embryos and cells , most notably via nuclear and gene transfer technologies, are considered w ith a view to identifying how detrimental consequences can be avoided.