RBMOnline - Vol 17 No 4. 2008 461-469 Reproductive BioMedicine Online; www.rbmonline.com/Article/3271 on web 19 June 2008 461 © 2008 Published by Reproductive Healthcare Ltd, Duck End Farm, Dry Drayton, Cambridge CB3 8DB, UK Lynette Scott has been working in the field of human IVF for 18 years, having started at King’s College Hospital in London. Prior to moving into the human field she worked on the early development of mouse embryos, getting her training and love of embryology from David Whittingham and Anne McLaren at the Mammalian Development Unit in London. She is native of Zimbabwe, Africa and obtained her BSc from the University of Cape Town and MSc and PhD from the University of London, University College. Her interest lies in the development of the oocyte and early embryo. Dr Lynette Scott Lynette Scott 1,3 , Jørgen Berntsen 2 , Darlene Davies 1 , Jens Gundersen 2 , Joseph Hill 1 , Niels Ramsing 2 1 Fertility Centres of New England, Reading, MA, USA; 2 Unisense FertiliTech, Science Centre Skejby, Aarhus, Denmark 3 Correspondence: Tel: +1 781 9427000, ext. 583; Fax: +1 781 9429840; e-mail: scottl@fertilitycenter.com Abstract Oocyte and embryo selection are not highly successful, with fewer than 10% of oocytes in assisted reproduction resulting in a delivery. Techniques for oocyte and embryo selection rely on highly subjective morphology assessment, with few true quantitative techniques available. One aspect of oocyte health that could be considered is the ability to produce ATP through respiration. Using a non-invasive technology, the respiration rates of individual human oocytes were recorded in an attempt to correlate respiration and oocyte health with probable subsequent development. Oocytes used were either immature or mature, non-fertilized oocytes from a clinical assisted reproduction programme. Differences in respiration rates between oocytes within a cohort and between cohorts of oocytes were recorded. The differences between cohorts relected many of the currently known differences in oocyte health, related to age and FSH concentrations. However, within a cohort, differences between oocytes were observed, with some having high rates and others low. Oocytes with respiration rates of between 0.48 and 0.55 nl O 2 /h were viable, with lower rates consistent with lack of continued in-vitro maturation or atresia. This technology may have a future in the clinical laboratory as a predictor of oocyte health and ability to develop into an embryo with greater potential of delivery. Keywords: non-invasive technology, oocyte selection, oocytes, respiration Successful embryo formation and subsequent delivery of an offspring requires that both gametes, oocyte and spermatozoon, must be fundamentally normal. Delivery of an infant should be the only measure of success after assisted reproduction treatment. Sperm (gamete) and embryo morphology are the most common and standard techniques of selection in assisted reproduction, and these are subjective and visual. Neither is exact; the ‘bell curve’ for success in these selection techniques can be rather wide, suggesting that there is an element of chance; approximately 10% of retrieved oocytes and fewer than 20% of transferred embryos result in a baby, worldwide (contributions from the Bertarelli Foundation, 2006). This is due most likely to patient proile and infertility aetiology, which can be relected in the quality of the gametes. In a technical setting, it can also be due to operator variance, lack of standardization of what constitutes normal, as well as other laboratory factors. What is clear is that, although the ield of assisted reproduction has become successful at a patient level, with more couples having deliveries; at the oocyte and embryo level, there is still substantial wastage. Symposium: Innovative techniques in human embryo viability assessment Human oocyte respiration-rate measurement – potential to improve oocyte and embryo selection? Introduction