Researchers have created the first-ever in-vitro rhino embryos in hopes that they can save the species from extinction.
Chemical and genetic techniques can be used to get embryonic stem cells to turn into any cell type desired, including egg and sperm cells.
Details of their experiment are published in the journal Nature Communications on July 4. Even the eggs of elderly or infertile SWR have produced embryos successfully.
The global team believes that assisted reproduction technologies used for other large mammals, including horses and cows, could be transferred to the surviving northern white rhinos as a way of boosting their reproductive capacity. This would be achieved by adopting the procedure pioneered here, to oocytes to be collected from the last two living NWR females. It's the most closely related subspecies, with more than 20,000 southern rhinos living in the wild.
Getting this far was no easy feat, however, as the team explained that it had to create an entirely new extraction device just to obtain an oocyte (egg) from the female rhino. To retrieve eggs, the researchers put the animal under anesthesia, and then used an ultrasound machine to guide a long needle into her uterus, puncture her follicles and dislodge the eggs.
"Clearly it's good news, it's a step in the process to eventually being able to create a purebred northern white rhino calf through IVF [in vitro fertilization]", said Olpajeta CEO Richard Vigne. The next step is to implant these embryos into surrogate southern females over the coming months, paper co-author Cesare Galli tells Yin, hopefully triggering the birth of a healthy hybrid calf.
"For fertilisation, the cryopreserved semen from deceased NWR males was used".
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It will also be a race against time, according to Thomas Hildebrandt, head of reproduction management at the Leibniz Institute for Zoo and Wildlife Research in Berlin. Only two female northern white rhinos are still alive and both are incapable of carrying a pregnancy, but they do still have viable eggs.
"Our results are solid, reproducible and very promising". For safe collection of female bio-material, the zoologists used a recently patented instrument with a length of almost two meters. The scientists performed more than twenty oocyte collections in SWRs within Europe, generating more embryos than those reported in the publication. This is why the scientists are working on an additional approach.
However, latest scientific advances in stem cell research brought Dr Hildebrandt and his worldwide team new hope in resurrecting the species.
"This would enlarge the founding diversity of the future NWR population substantially", the team said in a statement.
The emergence of new DNA sequencing technologies, cloning and cell reprogramming have opened up new opportunities for salvation while already extinct or endangered animal species.
However, as the technologies available at present cannot ensure proper transfer, the team has preserved the embryos so that they could be transferred into a female SWR when the time right.
Kock and fellow conservationists warned against focussing only on the northern white rhino sub-species, noting that its southern cousin has come back from the brink of extinction and now numbers some 21,000 individuals.