Oocyte cryopreservation entails important potential advantages for human IVF, offering a less ethically disputable alternative to embryo cryopreservation, simplifying and making safer oocyte donation, and giving an opportunity for fertility preservation to women at risk of premature ovarian failure as an effect of genetic factors or chemo- or radiotherapies. Oocyte cryopreservation could also meet the expectations of women wishing to preserve their fertility for social reasons. In the last few years, advances in cryopreservation methodologies have dramatically improved the efficiency of oocyte cryopreservation, leading to the birth of over a thousand babies and challenging the supremacy of embryo cryopreservation as the preferred form of fertility preservation. This text has been conceived with the aim of offering a comprehensive view of the state of the art of oocyte cryopreservation. It covers fundamental concepts of low temperature storage (controlled rate slow cooling and vitrification), aspects of oocyte physiology relevant to the process of cryopreservation, essential biological and clinical evidence, and ethical implications of oocyte cryopreservation, thereby providing a complete overview of progress in this strategy in assisted reproduction.

The oocyte is the largest and most mysterious cell in the body of mammalian organisms. Through its growth and maturation, it reaches extreme levels of specialization, while maintaining at the same time a condition of totipotency. Its unique ability, in co-operation with the spermatozoon, to give rise to a fully developed organism formed from hundreds of different tissues and myriads of individual cells has inspired intellectuals of all ages. Oogenesis finds impetus and purpose in casting scientific perspective towards this unique cell for the benefit of scientists and assisted reproductive technology (ART) specialists. The authors of the chapters are distinguished authorities in their respective areas of competence. From the opening of the book the reader is lead on a fantastic voyage from the formation of the primordial oocyte to the development of the early embryo, passing through crucial processes of oogenesis, such as co-ordination of oocyte and follicle growth, gene expression and organelle reorganization during growth and maturation, epigenetic mechanisms, regulation of meiosis, totipotency, cell polarity, oogenesis in vitro and maternal regulation of early development.