The queen of a naked mole rat colony can have offspring into old age. Researchers have now found out which factors are responsible for this phenomenon, which is very rare in the animal kingdom. In contrast to humans and other mammals, naked mole rats are probably able to produce egg cells throughout their lives, write scientists led by Miguel Brieño-Enríquez from the Pittsburgh School of Medicine in the journal "Nature Communications".

The rodents, which are up to 15 centimeters long and have hardly any hair, live mainly in East Africa and can live to be around 30 years old. "Naked mole rats are the strangest mammals," said scientist Brieño-Enríquez, according to a university statement. "They live the longest of all rodents, almost never get cancer, don't feel pain like other mammals, live in underground colonies, and only the queen can have children. But to me, the most amazing thing is that they never stop having children - They don't have a decrease in fertility as they get older. We want to understand how they do that."

Three causes of lifetime fertility

Together with his colleagues, Brieño-Enríquez compared the ovaries of naked mole rats at different life stages with those of mice and found indications of three possible reasons for the lifelong fertility of the naked mole rat: Female naked mole rats had significantly more oocytes than female mice, while those in significantly fewer rates die off. For example, the researchers found 1.5 million egg cells in an eight-day-old female naked mole rat - 95 percent more than in a female mouse of the same age, even though the ovaries of the two animals are comparable in size.

Indications were also found that female naked mole rats formed new eggs over the course of their lives. Although only the respective queen of a colony reproduces, all other female naked mole rats are theoretically able to assume this position at any time.

An extraordinary discovery

"This discovery is extraordinary," said Ned Place of Cornell University College of Veterinary Medicine, who was also involved in the study. "It scratches the dogma established around 70 years ago, according to which female mammals are equipped with a finite number of egg cells around their birth, without any more being added afterwards." Now it is to be examined whether these findings can possibly also be used to better understand the human ovaries and fertility - or to develop drugs to support them.