With only two female northern white rhinos left on Earth, and facing imminent extinction, it's no wonder these species don't feel so randy. But things are looking up, as scientists are hoping to use stem cell, rather than sex, to extend a lifeline to the dying breed.

Scientists have made the first step forward in ensuring the survival of species on the brink of extinction, as they've turned frozen skin cells from two highly endangered species into stem cells that can be used to preserve - or even revive - them.

Jeanne Loring and her colleagues at the Scripps Research Institute created stem cells from frozen skin cells of the northern white rhino and the drill, a west African primate.

The northern white rhinoceros (Ceratotherium simum cottoni) is a highly endangered species with only seven specimens remaining in existence. All seven are in captivity with two in San Diego.

The drill (Mandrillus leucophaeus) is closely related to the baboons and even more closely to the mandrill. Drills are found only in Cross River State, Nigeria; South Western Cameroon; and on Bioko Island, part of Equatorial Guinea. They are among Africa's most endangered mammals, and are listed by the IUCN  (International Union for the Conservation of Nature) as the highest conservation priority of all African primates.

The number of drills have been declining in all known habitat areas for decades because of illegal commercial hunting, habitat destruction, and human development.

The best way to manage extinction is to preserve species and habitats but that is not always working, Oliver Ryder, director of genetics at the San Diego Zoo and co-leader of the study, said in a statement. Stem Cell technology provides some level of hope that they won't have to become extinct even though they have been completely eliminated from their habitat.

In 1972, conservationists in San Diego began freezing skin samples from endangered species, in hopes that science would find a way to use these cells to prevent species from going extinct, according to a MIT Technology Review report.

The Frozen Zoo in San Diego has skin cells and other tissue samples from more than 800 species.

And five years ago, Ryder decided to contact Loring about the possibility of using the samples from the Frozen Zoo to generate and store stem cells. He felt the frozen skin cells from threatened as well as extinct species from the Frozen Zoo could be used as a starter kit for new life.

The talk has led to great developments.

According to BBC, the stem cells were made from skin by a process of re-programming. In this process the retroviruses and other tools of modern cell biology are used to restore the cells to an earlier stage of development. At this stage they are said to be pluripotent, meaning they can be induced to form different kinds of specialized cell such as neurons and cartilage.

Scientists are currently studying the use of stem cell to cure human diseases. And they hope to be able to use stem cells to create eggs and sperm, which could be used for breeding and boosting the genetic diversity of endangered species.

Either induced sperm cells could be combined with the eggs from living animals through in vitro fertilization or both eggs and sperms might be generated from stem cells and the resulting embryos could be planted in live host animals.

Scientists believe that this technique would be much more reliable than cloning techniques where the frequency of success is very low, Loring said.

I think that work would be a lot easier ethically with endangered species than with humans, Loring said.