Dying northern white rhinos may yet make it

The fate of critically endangered northern white rhinos lies in the laboratory. With only two surviving  northern white rhinos left in the world, both of them female, scientists are scrambling to produce offspring for the dying subspecies through artificial means.

They have now achieved a measure of success with that.

After harvesting 10 eggs from the two female rhinos, a mother and daughter called Najin and Fatu, on August 22 in Kenya, a team of scientists managed to mature seven eggs and artificially inseminate them. They did so with frozen sperm harvested from two northern white rhino bulls, called Suni and Saut, through a process called Intracytoplasmic Sperm Injection.

“We were surprised by the high rate of maturation achieved as we do not get such [a] high rate (comparable to what we get with horse oocytes) with southern white rhino females in European zoos,” explained Cesare Galli, a former professor of animal reproduction and biotechnology at the University of Bologna who led the procedure.

“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,” Galli elucidated. “Now the injected oocytes are incubated and we need to wait to see if any viable embryo develop to the stage where it can be cryopreserved for later transfer.”

If viable embryos do develop from the successfully fertilized eggs, they will then be inserted into southern white rhino females that will serve as surrogate mothers. This complex procedure is necessary because neither Najin nor Fatu can reproduce naturally any longer.

Another team of scientists recently attempted to pull off a similar feat of artificial insemination with three critically endangered Sumatran rhinos held in captivity in Malaysia. These last-ditch efforts have failed, however. Of the three Sumatran rhinos in Malaysia, two females and a male, only one ageing female now survives after the male and a female have both died despite round-the-clock care.

Northern white rhinos, which are also known as square-lipped rhinos, once roamed far and wide in east and central Africa. They were hunted into virtual extinction in recent decades, however, largely for their horns as these keratinous protrusions are believed (falsely) by practitioners of traditional Chinese medicine to posses curative properties. Najin and Fatu, the last two survivors of their subspecies, live in Kenya’s Ol Pejeta Conservancy where they are protected under armed guard.