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Freezing and storing endangered lynx embryos keeps hope for the species alive

A pair of captive Iberian lynxes who were sterilized may get to pass on their genes, after all. Researchers from the Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin salvaged embryos and egg cells from the two cats during their sterilizations and now hope to implant the cells, which they are now keeping in frozen storage, into surrogate cats for future breeding. If they succeed, it will be great news for the Iberian lynx, which researchers say is now one of the most endangered animals on Earth.

The IZW researchers, using a procedure that their own institute had pioneered, obtained embryos from two Iberian lynx females that were living in captivity at breeding centers in Spain and Portugal run by the Spanish conservation initiative Iberian Lynx Conservation Breeding Program (ILCBPS). IZW and ILCBPS are long-term partners.

The two females, named “Azahar” and “Saliega” by their human stewards, were both exhibiting serious health problems that appeared to rule out them ever breeding again. Azahar, who lives at the the Centro Nacional de Reprodução de Lince Ibérico in Silves, Portugal, had required emergency cesarean-section operations during both of her last two breeding attempts due to complications, while Saliega, a resident of the Centro de Cría de el Acebuche, in Doñana, Spain, had come down with a mammary tumor in July 2012 after lactating her latest litter.

More breeding attempts might have caused either cat serious harm, so the ILCBPS researchers had both sterilized. But they made sure to extract and preserve Azahar’s final fertilized embryos—she underwent her sterilization procedure seven days after mating one last time—and a batch of unfertilized egg cells from Saliega. Then they placed the embryos and egg cells into liquid-nitrogen vats for long-term storage.

Those extractions remain in deep-freeze storage to this day at Madrid’s Museo Nacional de Ciencias Naturales de Madrid and may go into future use in the breeding program. The researchers plan to try to insert the embryos into a surrogate mother cat.

Any success at breeding more Iberian lynxes couldn’t come too soon for this cat species. Today’s Iberian lynx population numbers no more than 200 and is entirely confined to southern Spain. Like many other species, they are victims of human destruction of their habitats and food supplies—the species has lost altogether 80 percent of its range. Many specimens are killed by hunters or fatally hit by cars, as well.