The Ol Pejeta Conservancy has Thursday announced that four additional Northern White Rhino embryos have been produced from oocytes collected from Fatu (Sudan’s granddaughter).
Through a statement, the conservancy said that the embryos were harvested by the international consortium of scientists and conservationists who worked towards preventing the extinction of the northern white rhino through advanced assisted reproduction technologies.
“This is the most successful series of procedures – from oocyte collection in Kenya to in vitro fertilisation and cryopreservation in Italy – the team of Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), Safari Park Dv?r Králové, Kenya Wildlife Service, Ol Pejeta Conservancy and Avantea has ever conducted,” the conservancy noted.
Additionally, the team confirmed the successful sterilisation of the southern white rhino bull Owuan, which was conducted in December 2020.
The bull will now be introduced to the Ol Pejeta southern white rhino females that have been identified as potential surrogate mothers for future northern white rhino offspring.
Females Najin and Fatu at Ol Pejeta Conservancy, Kenya, are the only remaining northern white rhinos in the world.
Tourism and Wildlife Cabinet Secretary Najib Balala speaking on the milestone said that partners in the project should now embark on the next phase of the project – embryo transfer to the surrogate southern white females at Ol Pejeta Conservancy.
“We are eager to get the progeny from the project that will guarantee the survival of the species,” he said.
The Harvesting Process
The international consortium of scientists and conservationists called BioRescue led by Leibniz-IZW has been harvesting immature egg cells (oocytes) from the two females and artificially inseminating these using frozen sperm from deceased males in order to create viable northern white rhino embryos since 2019.
In the near future, the embryos will be transferred to southern white rhino surrogate mothers to create northern white rhino offspring.
On March 28th, 2021, 19 oocytes were retrieved from Fatu’s ovaries using a probe guided by ultrasound, after the animal was placed under general anaesthesia.
Fatu is the younger of the two northern white rhinos, Najin’s daughter and Sudan’s granddaughter.
Both the anaesthesia and the ovum pick up procedure went smoothly and without complications.
After incubating and maturing the egg cells at Avantea’s laboratory in Italy, 14 of them were fertilised with thawed sperm from deceased northern white rhino bull Suni using a procedure called intra-cytoplasmic sperm injection (ICSI).
Four fertilised oocytes developed into viable embryos that are now stored in liquid nitrogen along with the five embryos already created in previous procedures.
Embryo development was achieved with the help of Geri®, an innovative benchtop incubator with integrated continuous embryo monitoring capabilities designed to provide an individualised and undisturbed incubation environment, and donated by Merck.
During the most recent procedure, Najin, who is now 31 years old, was put under light sedation whilst standing and examined via ultrasound.
After the results of the ultrasound, the team decided not to attempt the procedure as she had not appeared to have developed enough promising oocytes. The consortium will soon thoroughly discuss if and how to continue the oocyte collections with Najin, as ethical risk assessments are a pivotal part of the programme.