Northern white rhino.
Scientists raise hybrid embryos to save northern white rhino. Pictured, Fatu, one of the only two remaining female northern white rhino, runs in her paddock on March 20, 2018 at the ol-Pejeta conservancy in Nanyuki, north of capital Nairobi. Sudan, the last male northern white rhino, has died in Kenya at the age of 45, after becoming a symbol of efforts to save his subspecies from extinction, a fate that only science can now prevent. TONY KARUMBA/AFP/Getty Images

Northern White Rhinoceros (NWR), the world’s most endangered mammal species, is on the brink of extinction, but recently, a group of scientists described a way that could prove critical in saving them.

After the last known male white rhino died in March, only two females, named Najin and Fatu, are left on the planet. As they cannot reproduce due to the lack of a male, scientists had to look for other ways to save them.

So, they developed assisted reproductive technologies, which helped with the creation of two hybrid white rhino embryos consisting of a genetic mix of the NWR and its closely related cousin, the Southern White Rhino (SWR), the Washington Post reported.

The embryonic hybrids were created after the researchers used previously frozen NWR sperm to fertilize carefully extracted eggs from an SWR using in-vitro fertilization. The embryos developed to the blastocyst stage, which increases the chances of pregnancy after implantation into a surrogate female.

However, as the technologies available at present cannot ensure proper transfer, the team has preserved the embryos so that they could be transferred into a female SWR when the time right. At present, SWRs are not on the brink of extinction like their cousins, which means sometime in the future, a family of hybrid rhinos with genetic material from both groups could be raised.

While this won’t bring back the complete species, it would be a major breakthrough and ensure genetic continuity for the northern white rhinos, even after they’ll go extinct. The researchers involved in the latest work even extracted stem cells from the embryos to create more of these hybrid embryos.

However, this won’t be the final step. According to the researchers, in order to bring back northern white rhino in the real world, they will need eggs as well as sperm from it.

This is why they have the ambitious plan to extract the eggs from living NWR females first and then breed the hybrid white rhinos. Once this is accomplished successfully, it will be theoretically possible to selectively breed the hybrids to dilute the traits of SWR and concentrate those of the extinct species, giving birth to a pure population of northern white rhino.

Though the idea sounds far-fetched and is far from being achieved anytime soon, if the team succeeds in its mission, it will be a major achievement breakthrough in animal conservation.

Over the decades, the population of northern white rhino kept declining due to extreme poaching. The animals were killed for their horns, a gram of which valued more than gold and served as a status symbol for many. Rhino horns even proved beneficial in the field of medicine.

The study titled, "Embryos and embryonic stem cells from the white rhinoceros," was published July 4 in the journal Nature Communications.

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