Oocyte and embryo preservation in wild animals: an update.

The reduction in population genetic diversity due to inbreeding depression and the negative impact of human activity on habitats ultimately generates an extinction debt. Therefore, there is always a dire need to save wild population and to protect biodiversity. Preservation of wildlife female germplasm, i.e., oocytes and embryos, is a promising biotechnological tool to conserve species' biodiversity. Other applied tools of Assisted Reproductive Technology (ART) which assure conservation of endangered species include artificial insemination (AI), embryo transfer technology (ETT), and sperm cryopreservation. Only a few studies show the possibility of adapting the cryopreservation techniques developed for domestic animal female genetic material for use with wild animals. Difficulty is encountered in getting samples, accesses to animals for study, and the standardization of protocols for cryopreservation of such genetic material. Our meta-analysis of the literature (published or in press) and on-going studies found that biobanking for the preservation of vital tissues of wild animals is possible. Somatic tissue sections, ovarian tissues, sperms, oocytes and embryos are potential materials for preservation by vitrification. As vitrification is economical and easily applied, it appears to the best option currently available for the preservation of wildlife female genetics in order to conserve species' biodiversity.