IN VITRO FERTILISATION COULD SAVE NORTHERN WHITE RHINOS FROM EXTINCTION
New hope for the survival of the northern white rhino has emerged with the creation of the first in vitro, hybrid rhino embryos.
With only two females left alive, the northern white rhino is classified as being functionally extinct. But an international team of scientists has combined cryopreserved semen from northern white rhino males with egg cells harvested from southern white rhinos to produce a viable embryo.
“These are the first in vitro produced rhinoceros embryos ever. They have a very high chance of establishing a pregnancy once implanted into a surrogate mother,” said Prof Thomas Hildebrandt of the Leibniz Institute for Zoo and Wildlife Research in Berlin.
The team adapted a technique used for assisted cattle and horse reproduction to harvest oocytes (immature egg cells) from captive southern white rhino females. Harvesting oocytes from rhinos is tricky because their ovaries can’t be reached by hand and lie next to a major artery that could cause a fatal bleed if punctured. To get around this the team developed a two-metrelong, ultrasound guided device to safely extract the oocytes.
The extracted oocytes were then combined with northern white rhino sperm and cultured until a blastocyst, an early form of an embryo, developed.
“Our results are solid, reproducible and very promising. Now we’re well prepared to go to Kenya and collect oocytes from the last two northern white rhino females to produce pure northern white rhino blastocysts,” said Hildebrandt.
But having only four males’ frozen sperm and two living females means subsequent generations of northern white rhinos won’t have the genetic diversity necessary to propagate the species. So the scientists are planning to use stem cell technology and northern white rhino tissue to create new reproductive cells that can be transplanted into the rhinos’ sperm and eggs.
Fatu ( pictured) and her mother Najin are the only northern white rhinos left