Cryopreservation - a Chance for Highly Endangered Mammals
Oocytes of lions, tigers and other cat species survive the preservation in liquid nitrogen
Scientists of the Leibniz Institute for Zoo and Wildlife Research (IZW) succeeded in carrying out cryopreservation of felid ovary cortex.
“We have successfully frozen and thawed oocytes in the ovary cortex of different cat species at minus 196 degrees Celsius. This freezing process and the storage of living cellular material in liquid nitrogen is called cryopreservation”, said Caterina Wiedemann, doctoral candidate at the IZW.
The ovarian cortex is regarded as a reservoir of reproductive cells. It contains thousands of immature oocytes. Successful cryopreservation of ovarian tissue of wild cats is therefore a key element for the establishment of genome resource banks, an important tool for the preservation of genetic diversity. All felid species except for the domestic cats are listed on the Red List for endangered species of the International Union for Conservation of Nature (IUCN).
Taking a freezing procedure developed in human medicine as their model, scientists at the Department of Reproduction Biology of the IZW developed a method for cryopreserving the ovarian cortex of different cat species. In the original procedure, ovarian tissue of women who suffer from cancer is removed to avoid its damage by chemotherapy or radiotherapy. After successful tumor treatment the tissue is re-transplanted so that the normal female cycle, including fertility, can be restored. In the meantime, the tissue is conserved in liquid nitrogen. The IZW adapted this method to preserve female germ cells from feline species.