Effects of fertility preservation on oocyte genomic integrity

An important adjunct to the field of fertility preservation is cryobiology. At present, the long-term storage of oocytes, embryos or ovarian tissues relies upon cryopreservation technologies that fall into roughly two different modalities: traditional slow freeze (SF) or rapid cooling, often invoking the process of vitrification. Unlike most cells in the body, female germ cells or oocytes present unique biophysical constraints as either isolated entities or within the context of ovarian follicles. Especially relevant is the fact that the oocyte nucleus, often referred to as the germinal vesicle, is highly hydrated and presents a voluminous non-chromatin occupied space that undergoes significant alterations in chromatin organization during its development. While the impact of cryopreservation on the integrity of the oocyte plasma membrane, organelles, and spindle cytoskeleton have been the focus of most studies to date, the short-term and long-term consequences of chilling and cryoprotectants on the chromosomal and genomic integrity has received much less attention. This chapter reviews the topic of genomic integrity at the level of the oocyte and provides guidelines for the design and implementation of strategies that will permit objective assessment of current and future protocols applied in the field of fertility preservation.