There is no clearer testament to the importance and efficacy of in vitro fertilization in the treatmentof the infertilepatient than the fact that over one million babies have been born since its clinical introduction in 1978. The successof this worldwideendeavorhas evolvedto treat some of the formerly most intractable forms of infertility and requires individuals with different skills and insights whose activities are often compartmentalized into clinical, laboratory and research functions. The intent of Essential l VF is to present current issues in clinical IVF that encompass the varied activities of those engaged in this enterprise. By integrating clinical, basic research and laboratory-related aspects of human reproduction, readers with diverse interests should obtain a more complete understanding of the impact, importance and inter-relatedness of each in the progress of infertility treatment, and an appreciation of whether emerging technologies will or should contribute to this progress in the near future. The topics selected for this volume include research that has begun to explain the origins of differential follicular, gamete, embryo and uterine competence, and specific laboratory procedures and protocols that may have important clinical implications forthe generation ofdevelopmentally viable embryos. Human embryoresearchoverthe past 25 years has notonly confirmed that the developmental potential of each embryo is unique, but more importantly, demonstrated how genetic and nongenetic factors for sperm and oocyte determineembryo competencewell before fertilization. Several chapters deal with the origins of normal and compromised gametes and how those with high competence can be identified and isolated for fertilization.