For the functionally extinct northern white rhinoceros (Ceratotherium simum cottoni), there may be some hope. Although just two females of these rhinos remain, scientists recently created hybrid embryos from southern white rhino (Ceratotherium simum) eggs and the sperm from deceased northern white rhinos using assisted reproduction techniques. This is the first time pre-implantation embryos for rhinos were created in test tubes, according to the researchers. To bring the northern white rhinos back from the brink of extinction, the team plans to collect oocytes — immature egg cells — from the two remaining northern white rhino females in Kenya and fertilize them with deceased male northern white rhino sperm. They believe they have a good chance of establishing a pregnancy with these materials in a surrogate female southern white rhino.