Embryos from the eggs of southern white rhinos and sperm of northern white rhinos have been created in the lab. The successful fertilization, reported July 4 in Nature Communications, is a small step toward researchers’ long-term goal of resurrecting the northern white rhino population, which is on the brink of extinction.
“These are the first in vitro produced rhinoceros embryos ever,” study coauthor Thomas Hildebrandt, head of the Department of Reproduction Management at the German Leibniz Institute for Zoo and Wildlife Research in Berlin, says in a statement. “They have a very high chance to establish a pregnancy once implanted into a surrogate mother.”
In vitro fertilization is the last hope to save the northern white rhinos, a subspecies of white rhinos, since the last male died in March. Only two female northern white rhinos are still alive and both are incapable of carrying a pregnancy, but they do still have viable eggs.
The embryos have been frozen for now, but Hildebrandt and his colleagues hope to eventually impregnate a female southern white rhino as a surrogate. In March, scientists working with the San Diego Zoo showed this was possible, successfully impregnating a southern white rhino via artificial insemination.
Harvesting eggs from the two living northern white rhino (NWR) females is also a possibility. “Our results are solid, reproducible and very promising. Now we are well prepared to go to Kenya and collect oocytes from the last two NWR females in order to produce pure NWR blastocysts where both eggs and sperm are from NWR,” Hildebrandt notes in the statement.
Despite the success, there are still doubts about resurrecting the animals. “We have a long way to go to save the northern white rhino,” Terri Roth of the Cincinnati Zoo & Botanical Garden who was not involved in the study tells Newsweek. “Impressive results in a petri dish don’t easily translate into a herd of healthy offspring.”