Harvesting eggs of last northern white rhinos may save species

There are only two northern white rhinos left in the world – Najin and Fatu, two females, both unable to carry a calf. But there’s hope for the species: on Aug. 22, scientists were successful in harvesting eggs from the pair.

The eggs were immediately sent to Italy, where researchers have attempted to fertilize them with cryogenically frozen sperm from four deceased male members of the species.

“We were able to harvest a total of 10 oocytes – five from Najin and five from Fatu – showing that both females can still provide eggs and thus help to save these magnificent creatures,” said Dr. Thomas Hildebrandt from the Leibniz Institute for Zoo & Wildlife Research. “Both the technique and the equipment had to be developed entirely from scratch.”

Any resulting embryos will be frozen until southern white rhino surrogates can be found. 

The new procedure brings hope for the species that has been functionally extinct since March 2018, when the last male northern white rhino died.

“We are delighted that this partnership gets us one step closer to prevent extinction of the northern white rhinos,” John Waweru, director general of the Kenya Wildlife Service, told the Daily Mail. “This is particularly touching given the heartbreaking death of Sudan, the last male, who died of old age last year in Kenya.”

There are still challenges ahead, even if the in vitro fertilization goes well. Harvesting eggs from the two females is limited to three times per year; any more would risk their health. And working from a pool of two females and four males could cause a major genetic bottleneck in the species. 

However, scientists do have access to frozen tissues from other northern white rhinos. The group BioRescue is hoping to create artificial sex cells using those genomes to increase the diversity of rhino embryos in the future. 

Researchers are hoping to re-introduce the northern white rhinos – one of five rhino species – back into their natural habitats. But poachers still pose a major danger; it was poaching for ingredients for traditional Chinese medicine and dagger handles in Yemen that reduced the northern white rhino numbers so drastically, the Daily Mail reported. 

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By Kyla Cathey, Earth.com staff writer