Advances in the development and application of electron microscopic techniques have occurred recently such that the electron microscope has evolved to become an essential tool in both basic and clinical research. Use of this instrument has contributed significantly to the formation of new perspectives and concepts concerning cell fine structure. These structural perspectives are now being integrated with specific functional, biochemical and pathophysiological events and processes of cells and tissues. Most recently, utilization of innovative electron microscopic techniques such as freeze-fracture, freeze etching, and scanning and high-voltage electron microscopy offers both the basic and clinical scientist potentially fundamental insights into many morphodynamic processes related to the activities of cells and tissues. Such an approach has been especially rewarding when applied to the dynamic events of gametogenesis and early embryonic development. The chapters comprising this book have been selected and edited with the aim of providing an up-to-date and comprehensive account of the most important aspects of vertebrate gamets and embryos as revealed by the integration of several different submicroscopic methods. The organization of the chapters is designed to indicate present gaps in our knowledge of the developmental and reproductive biology of gametes and the developing embryo and possible Iines of research which may lead to a lessening of these gaps."

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 lVF 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.

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 lVF 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.

In the last few years, the adoption and worldwide proliferation of clinical procedures for medically assisted conception have been associated with the examination and analysis of spermatozoa, oocytes and early embryos under a variety of in vivo and in vitro conditions. These analyses have enabled correlations to be made between the behavior of gametes, the pattern of early embryonic development and the initiation of a normal pregnancy. Collectively, the findings have not only enormously increased our understanding of the process of early human development, but also have provided new insights into the origin and causes of reproductive failure in man. The research presented in this volume describes recent results derived from the study of normal and abnormal patterns of human spermatogenesis, oogenesis and early embryogenesis. The chapters discuss aberrations in morphodynamic and morphophysiological processes that have clinical relevance in human infertility and conception. Two of the chapters describe, respectively, the basic research that allows the cryopreservation of human oocytes and embryos, and the development of in vitro systems that permit the study of cell differentiation and interaction during the peri-implantation period. When relevant, each chapter extrapolates findings from in vitro experimentation to the comparable situation that is observed in vivo.