Human assisted conception: a cautionary tale. Lessons from domestic animals

A variety of embryo-based technologies used in farm animal reproduction, in cluding embryo culture, nuclear transfer, embryo-somatic cell co-culture an d asynchronous embryo transfer can lead to the production of large offsprin g; the so-called large calf/lamb syndrome. In some cases, abnormalities in the fetus and newborn are apparent. The nature of these associations is exp lored with emphasis on the biological differences between in-vivo- and in-v itro-produced embryos, A undying framework and research programme aimed at explaining anomalies in early embryo development is then proposed in terms of the response of somatic cells and embryos to cellular stress. The re,iea concludes with a caution against developments in assisted conception techn ologies, in man and domestic animals, being determined too much by the need s of commerce at the expense of research on the molecular, biochemical and physiological basis of early mammalian development.