First step in plan to save northern white rhino
Just five of the animals remain on the planet, after two adult males died within months of each at the end of 2014.
At a meeting in Nairobi, Kenya, on Tuesday, conservationists decided to harvest eggs from the remaining females.
The eggs will be stored with a view to being used for IVF in the future.
While offering some hope for the rhino sub-species, it also underlines the dire prospects for the last animals.
The eggs will join northern white rhino sperm already stored by an institute in Berlin, Germany.
Experts say IVF will only be attempted after techniques improve, but have set no expected timeframe on this threshold.
After harvesting the oocytes (immature egg cells), experts will "wait for a time when the IVF techniques will be developed and tested enough to give us a reasonable chance that usage of (northern white rhino) samples would lead to a successful embryo transfer", said Jan Stejskal, from the Dvur Kralove zoo in the Czech Republic, which owns the last animals.He told BBC News: "This still needs to be carefully discussed with the experts in the field, but in general we can say we decided to do a first step towards IVF."
Many of the remaining animals are of advanced age, and by the time IVF becomes possible, scientists might have to implant an embryo in a surrogate female from the northern white's close relative, the southern white rhino.
Mr Stejskal said there was no current plan to use artificial insemination as a strategy. This had previously been a theoretical possibility for one of the animals, Naijin, which lives at the Ol Pejeta Conservancy in Kenya.
2014 turned out to be an annus horribilis for the sub-species. On 17 October, a 34-year-old male called Suni died of a suspected heart attack at the Ol Pejeta Conservancy in Kenya.
Then, on 14 December, Angalifu, a 44-year-old male living at San Diego Zoo in the US also passed away.
The last remaining male is 43 years old - elderly by rhino standards - and is considered incapable of mating on his own.
Experts have already taken the first steps towards harvesting eggs from Nabire, a 31-year-old female living at the Dvur Kralove Zoo. But the procedure in October last year had to be stopped out of concern for the health of the animal. But the scientists could resume the effort at some point soon.