The availability of cryopreservation technology has extended the scope of
human-assisted conception treatment and made it more convenient for patients.
Freezing of oocytes and ovarian tissue is now taking place in research institutions and
should hopefully become widely available for clinical use in the future if the women
have to be away at a critical time during the treatment; the frozen oocyte was thawed
and used when required. Good quality embryos frequently remain after the transfer of
the required number into the woman; these can be frozen and used at a later date, if
required, instead of the couple going through another cycle of in vitro fertilization
(IVF) treatment. The conduct of cryopreservation in humans is based on information
originally derived from animal work, where sperm cryopreservation, for example, has
been carried out for several decades for animal breeding. This chapter will consider the
principles of cryopreservation followed by a general description of the practical steps.
The clinical applications of cryopreservation will also be described. A final section will
deal with frozen embryo replacement.
Keywords: Oocyte and embryos cryopreservation, Slow freezing, Thawing embryos, Vitrification.
