Next stop extinction? 32-year-old Najin, one of the world's last two northern white rhinos, won't have her eggs harvested to help a breeding program save the species as old age and illness take their toll

 Scientists said on Thursday that Najin, one of the world's last two northern white rhinos, is retiring from the breeding program to save the species. 

Najin, 32, will not have her eggs harvested as a result of her retirement, with researchers noting that old age and illness are impacting her. 

The other northern white rhino, Fatu - Najin's 20-year-old daughter - is the only donor left in the program, which is trying to implant artificially developed embryos into female southern white rhinos. 

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Najin, one of the world's last two northern white rhinos (pictured), is retiring from the breeding program to save the species.

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She will not have her eggs harvested as old age and illness are impacting her

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Doctors found multiple, small benign tumors in her cervix and uterus and a 25 centimeter cyst in her left ovary

'In a special, in-depth ethical risk assessment, the team has reached the decision to retire the older of the two remaining females, 32-year-old Najin, as a donor of egg cells (oocytes),' BioRescue said in a statement. 

'This leaves the ambitious program with just one female that can provide oocytes, Najin's daughter Fatu.' 

Najin's advanced age, and signs of illness, were also taken into account, they said. 

Recent medical examinations of Najin found 'multiple, small benign tumors in her cervix and uterus, as well as a 25 centimeter cyst in her left ovary.

'These findings might explain why oocyte collections were not as successful with her as with Fatu,' said Leibniz-IZW head veterinarian Dr Frank Göritz and Ol Pejeta head veterinarian Dr Stephen Ngulu.

'This is why we came to the conclusion that the most valuable role for Najin is to be an ambassador for the conservation of her kind and to ensure that she can transfer her social knowledge and behavior to offspring in the foreseeable future.' 

There are no known living males and neither of the two remaining northern white rhinos can carry a calf to term.

Northern white rhinos, which are grey in appearance used to roam across Africa, in some cases living up to 50 years old.

However, widespread poaching of the animals dropped the numbers precipitously, with just Najin and Fatu left. 

The researchers said other measures were considered, but they felt this was the best thing for the species as a whole.

'We are well aware of the fact that we are pushing the boundaries of what is do-able in conservation and that this requires us to also think about ethical and moral implications', said BioRescue project head Prof Thomas Hildebrandt in the statement. 

'Every procedure of the program is accompanied by a full ethical risk assessment and we are convinced that we should not do anything we could do just because we can. 

'Developing clear ethical principles based on our knowledge, scientific expertise in animal welfare ethics and decision making, and a vigilance towards societal discourse is a fundamental basis of BioRescue.'

A Biorescue team led by researchers from the Leibniz Institute for Zoo and Wildlife Research in Germany has been racing against time to save the world's most endangered mammal.

In July, scientists created three more embryos to help save the functionally extinct northern white rhino, bringing the total to 12 embryos they have created so far.

Scientists hope to implant the embryos made from the rhinos' egg cells and frozen sperm from deceased males into surrogate mothers, likely southern white rhinos.

It is estimated there are around 18,000 southern white rhinos left in the world, with a status that is classified as 'near threatened,' according to the World Wildlife Fund.   

'We have been very successful with Fatu... So far we have 12 pure northern white rhino embryos,' David Ndeereh, the acting deputy director for research at the Wildlife Research and Training Institute, a Kenyan state agency, told Reuters.

'We are very optimistic that the project will succeed.' 

The first batch of embryos was created in 2019. 

Since 2019, Biorescue has collected 80 eggs from Najin and Fatu, but the 12 viable embryos all hail from the younger rhino. 

The team hopes to be able to deliver its first northern white rhino calf in three years and a wider population in the next two decades.

Modern rhinos have roamed the planet for 26 million years and it is estimated that more than a million still lived in the wild in the middle of the 19th century. 

SCIENTISTS PIN HOPES ON IVF TO SAVE THE NORTHERN WHITE RHINO FROM EXTINCTION

While the death of Sudan marks a symbolic turning point in the fight to save the northern white rhino, in fact the survival of the species has been entirely reliant on untested IVF techniques for years.

It was hoped that Sudan, his daughter Najin and granddaughter Patu might be able to produce offspring when they were moved to Kenya in 2009, but their close genetic relationship rendered them infertile.

Since at least 2015 scientists have been working with IVF and stem cell techniques in the hopes of being able to create a viable northern white rhino embryo, according to a GoFundMe page for the project.

Researchers in Berlin and San Diego are using DNA samples collected from a dozen northern whites, including Sudan, and trying to apply techniques developed for humans to the animal.

If a viable embryo can be created, it would then have to be implanted into the womb of a southern white rhino, since Majin and Patu will likely be dead before the technique is perfected.

While the southern white rhino would be responsible for giving birth to the baby, because the infant's genetic material came solely from northern whites, it would be a member of that species.

However, as Save The Rhino points out, the process is fraught with difficulty and has a low chance of success.

In the last 15 years just 10 rhino births have resulted from artificial insemination and only two embryos have ever been created - one of which divided into two cells before perishing, and the other one into three.

For the northern white rhino to be genetically viable a minimum of 20 healthy individuals must be born - meaning the whole process must be successfully completed 20 times - to avoid inbreeding.

Then, it would be necessary to find a suitable habitat for them, since their old habitat has largely been destroyed and led the species to the brink of extinction in the first place.