African rhino in the Savanna at sunset

Scientists fertilize eggs from last northern white rhinos

Scientists working to save the northern white rhinos from extinction, a species of which only two females remain in the world – Najin and Fatu – announced today that 7 of the 10 eggs taken from these animals in the past were fertilized Friday in Kenya in a groundbreaking operation.

The eggs were artificially inseminated with frozen sperm from two males, Suni and Saut, and four of them belong to Fatu and 3 to Najin, the Kenyan Wildlife Conservation Service (KWS) said in a statement on Monday.

Operation performed for the first time

Maturation and fertilization, completed in an Italian laboratory, were crucial steps in obtaining potentially viable embryos that could then be transferred to southern white rhino “surrogate mothers”.

In the extraction operation, carried out for the first time in history last Friday in the Kenyan reserve of Ol Pejeta (where the two females live), a total of 10 immature eggs had been obtained, so the scientists have been satisfied with the results achieved.

We are surprised by the high maturation rate achieved since we do not see such a high rate, comparable to what we obtain with oocytes (immature precursors of ovules) from horses, with female southern white rhinoceros in European zoos.

Saut’s semen was very difficult to work with and to find the three live sperm needed for Najin’s eggs we had to thaw two semen samples, added the scientist from the Avantea laboratory, specialized in reproduction.

Embryo development

Now, the inseminated eggs will go through an incubation process and it is expected that around September 10 it will be announced whether embryos developed enough to be cryopreserved and later transferred for gestation were achieved.
The procedures have been the result of years of research and practice within the international “BioRescue” program.

Those responsible behind this milestone are the Leibniz Institute for Zoological and Wildlife Research Berlin (Leibniz-IZW), Avantea, the Czech Dvur Kralove Zoo, Ol Pejeta Conservancy and the Kenya Wildlife Service (KWS). funded by the German Federal Ministry for Education and Research.

Najin and Fatu, the world’s last two remaining northern white rhinoceros , were brought to Kenya from the Czech Republic in 2009 along with two males, Suni (died 2014) and Sudan, in the hope that their habitat naturally will stimulate procreation.

Sudan, the last surviving male (father of Najin and grandfather of Fatu), was euthanized in March 2018 after significantly aggravating the ailments he suffered.

With the aim of saving the northern white rhinoceros from extinction, a species of which only two females remain in Kenya – Najin and Fatu – a group of scientists has extracted their eggs for the first time to be fertilized “in vitro”.

white rhinoceros

Two unique specimens of white rhinoceros

The process was very delicate. They are the only two (northern) white rhinos left in the world. The anesthesia used was highly sensitive and required a lot of teamwork and preliminary studies. We use the rhinoceros immobilization protocol (and) monitor the physiological parameters. The animals were calm and everything went very well.

In vitro fertilization

Now these eggs will be fertilized “in vitro” in a laboratory in Italy with the frozen sperm of Suni (died in 2014) and Sudan, the last male northern white rhinoceros, sacrificed in March 2018 in Ol Pejeta after worsening the disease he suffered .

Later, if there is an embryo, they will be implanted in female southern white rhinoceros, the scientists detailed, since both Najin and Fatu are sterile.
The procedure has been the result of years of research and practice, developed within the international “BioRescue” program, which has borne fruit with the extraction of a total of 10 eggs, five from each female.

Those responsible behind this milestone are the Leibniz Institute for Zoological and Wildlife Research Berlin (Leibniz-IZW), Avantea, Dvur Kralove Zoo, Ol Pejeta Conservacy and the Kenya Wildlife Service (KWS), funded by the Federal Ministry of Education and Research of Germany.

Both the technique and the equipment had to be developed entirely from scratch referring to the ultrasound-guided probe that allowed them to extract immature eggs (oocytes), operation carried out this Thursday.

The two females, Najin and Fatu, were transferred to Kenya from the Czech Republic in 2009 along with two males, Suni and Sudan, in the hope that their procreation would be stimulated by being in their natural habitat.

After several unsuccessful attempts, it was discovered that the two females could not become pregnant, and after the death of the only two males it was decided to freeze their sperm for future assisted reproduction.

On the one hand, Ol Pejeta is sad that there are only two specimens of northern white rhinoceros left on the planet, a reserve where the two females live.

However, I am also immensely proud to be part of this pioneering work to save this species and hopefully that this is the beginning of an era in which humans understand that the environment is not a luxury but a necessity.

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