Scientists working to save the northern white rhino have artificially inseminated seven of 10 eggs successfully harvested last week from the world’s last two remaining individuals currently living at the Ol Pejeta Conservancy in Kenya, according to Berlin-based research association FVB. If the eggs take, they will be transferred to a southern white rhino surrogate mother – a feat that may save the northern white rhino from complete extinction.
“On the one hand Ol Pejeta is saddened that we are now down to the last two northern white rhinos on the planet, a testament to the profligate way the human race continues to interact with the natural world around us,” said conservancy managing director Richard Vigne. “However, we are also immensely proud to be part of the groundbreaking work which is now being deployed to rescue this species. We hope it signals the start of an era where humans finally start to understand that proper stewardship of the environment is not a luxury but a necessity.”
A process called intracytoplasmic sperm injection allowed for researchers to mix the sperm from two now-dead northern white rhino bulls, Suni and Saut, whose sperm was cryo-preserved after they died of natural causes in 2014 and 2019, respectively. Two batches of the frozen semen were used and took to four of Fatu’s eggs and three from Najin, according to the conservation organization Helping Rhinos.
“We were surprised by the high rate of maturation achieved as we do not get such high rate (comparable to what we get with horse oocytes) with southern white rhino females in European zoos. The semen of Saut was very difficult to work with and to find three live sperms needed for the eggs of Najin we had to thaw two batches of semen. Now the injected oocytes are incubated and we need to wait to see if any viable embryo develops to the stage where it can be cryopreserved for later transfer,” said Cesare Galli, who led the fertilization procedure, in a statement.
Northern white rhinos are a subspecies of the white rhino whose range once covered much of central Africa. Poaching and other human activities have forced Ceratotherium simum cottoni to extinction in the wild, despite other rhino species making a comeback in recent years, according to the International Union for Conservation of Nature. The last two remaining female white rhinos are too old to carry offspring. Earlier this year, IFLScience reported that the team had successfully transferred the first test-tube rhino embryo into a surrogate southern white rhinoceros – an important milestone in using reproduction and stem cell technology to restore the species to historic levels. Researchers say their latest endeavor is the next step in creating viable embryos that will then be transferred to southern white rhino surrogates.
"The procedure was the result of years of research, development, adjustments, and practice. “Both the technique and the equipment had to be developed entirely from scratch,” said researcher Thomas Hildebrandt in a statement at the time. “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.”
The results of the embryo development research will be announced in mid-September.