Tadpoles from the Freezer
First the sperm had to be collected: this was done by injecting the animals with hormones. Next the sperm had to be stored safely. Cryopreservation is the storage of viable body cells at -200° Celsius. Sperm cannot be simply frozen and thawed; this would lead to the cells not being viable. Live, highly fertile sperm can be obtained by cryopreserving the cells in a carefully created cocktail and freezing and thawing them in a specific way. Even after a number of months at -200° degrees, successful development of tadpoles was seen.
A combination of rearing programs and an amphibian sperm bank can offer help for threatened amphibian species. Although there had been earlier success in Russia rearing tadpoles with frozen sperm from dead amphibians, this is the first time that sperm has been harvested successfully, without side effects, from living animals.