Recently the International Union for Conservation of Nature (UICN), announced that after more than six years of warning about the critical state of survival of the northern white rhinoceros, the species is functionally extinct because only two females survive in the world, so they can no longer reproduce .
These mammals lived for decades on the lookout for poachers, the main threat to the species, due to the high commercial value of their horns in Asia.
In December 2014, the UICN announced that only five northern white rhinoceros were still alive (four females and one male) and classified the species as critically endangered.
A year later, two females of the group died and the chances of saving the subspecies were drastically reduced.
Finally, the last male died in March 2018 without reproducing with any of the females.
The only hope to save the subspecies is to find some male specimen in the wild, which is a remote possibility, since it is considered that these could be extinct in the wild.
However, once the last male northern white rhinos died, biologists risked a last wager on the development of science and saved sperm samples to attempt in vitro fertilization.
In 2019, a team from Leibniz Institute for Research and Wildlife managed to take the first step and extracted ovary tissue from female rhinos to grow immature eggs with the intention of fertilizing them and creating embryos of northern white rhinoceros.
Currently, there are some frozen embryos awaiting implantation in a female southern white rhino, the species most similar to northern white rhinos. However, sperm and eggs are limited and the process for their development in vitro is not yet entirely clear in this species.
Therefore, scientists have worked on a way to create more mature eggs from the tissue of deceased female ovarian follicles. Because rhinos do not go through menopause, the ovaries of old specimens keep creating these follicles into old age.
The development of this technique opens up a possibility to save not only the northern white rhino, but all currently threatened rhino species.
HH
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