Only the last two northern white rhinos remain in the world and both are females, so this subspecies can no longer reproduce naturally and its extinction would seem inevitable.
Around 1980 the population of these animals was around 500 specimens, declining dramatically at the beginning of this century, until today there were only two.
It was poaching and the indiscriminate advancement of agricultural borders with the consequent disappearance of habitats that led this subspecies to such a critical situation.
Therefore, several attempts have been made to reproduce this species in an artificial way.
In some species, when those left are only males and in the best case frozen eggs of that same species, what is done is, as a rented womb, to use the womb of a related species that is not in danger to act, as if it were an incubator, as a carrier of the material genetic status of the species at risk.
That species, for example, the domestic cat, as a “rented” womb of endangered wild cat species, is the mother carrying the embryos, but not the genetic mother.
That way you can save a species of which few specimens are left on earth.
Retrocrossing or crossing by absorption can also be used as a methodology when we have males of the endangered species and females of nearby species to which it will mate or inseminate, and then the procedure is repeated with its products for several generations until we obtain what is defined as a “pure by crosses”. An individual who will have almost 100% of the genetic material of the endangered species.
In the case of northern white rhinos, the situation is much more complex. There are only two females, there are no males and frozen semen is scarce.
On the one hand, researchers are developing advanced assisted reproduction techniques, and secondly, they want to use cells extracted from the northern white rhino to create pluripotent stem cells that can become immature eggs or oocytes.
These cells, in this case of the skin, have the potential to become any cell of the body, including germ cells, the northern white rhino oocytes, necessary for the reproductive process.
Meanwhile, progress is also being made in assisted reproduction.
In this idea, they collected immature eggs and managed to inseminate it with thawed sperm from a dead male, generating a viable northern white rhino embryo.
There are currently a total of 14 northern white rhino embryos, which are stored in liquid nitrogen at minus 196 degrees Celsius.
In the near future, the embryos will be implanted in southern white rhino, with the aim of creating a healthy young of northern white rhino.
*Prof. Dr. Juan Enrique Romero @drromerook is a veterinary physician. Specialist in University Education. Master's Degree in Psychoimmunoneuroendocrinology. Former Director of the Small Animal School Hospital (UNLPAM). University Professor at several Argentine universities. International lecturer.
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