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Sand naked. These rodents remain fertile throughout their lives. We already know why

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Sand molluscs, as one of the few mammals, are able to reproduce throughout their lives. American scientists have discovered what this has to do with. Researchers hope that the discovery of the unusual process will become the basis of infertility therapy in the future.

Sand naked (Heterocephalus glaber) are some of the strangest mammals known to science. These animals can live over 30 years, much longer than all other rodents, almost never develop cancer and feel some types of pain, and they live under a strict caste system. Scientists are puzzled by one more fact from the life of rodents – their fertility does not decrease with age. The study of this unusual trait of naked mole rats was recently published in the journal Nature Communications.

Three Ways to Fertility

In most mammals, females are born with a certain number of eggs, which are produced during fetal life and mature when the individual reaches sexual maturity. This limited supply of eggs is depleted over time – some are released during ovulation, but most simply die. For this reason, the fertility of most species decreases with age, but this relationship is not observed in mole mole rats.

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“There are three strategies to circumvent this problem: naked mole rats can be born with a large number of eggs, they can be resistant to dying, or the animals can produce new cells after birth,” explains Miguel Brieño-Enríquez of the University of Pittsburgh, the lead author of the study. – My favorite hypothesis is that naked moles use all three.

Sand char (Heterocephalus glaber) – pic. illustrativeAdobe Stock

Dogma undermined

To find out why the rodents are so fertile, the researchers compared the ovaries of naked mole rats and mice at different stages of development. Despite their similar size, the mice live at most four years and begin to show a decline in fertility after nine months of age. As it turned out, female naked mole rats have an exceptionally large number of oocytes, and the rates of egg cell death are very low. For example, at the age of eight days, female mole rats have an average of 1.5 million eggs, about 95 times more than mice of the same age.

Most interestingly, the study also showed that adult mole rats are in the process of forming new eggs. The oocytes that give rise to the eggs were actively dividing in three-month-old animals and were present in 10-year-old females.

“This is a remarkable finding,” said Ned Place of Cornell University, co-author of the study. – It challenges the nearly 70-year-old dogma that female mammals are endowed with a finite number of eggs.

“Any girl can be a queen”

The unusual fertility of naked mole rats seems to be related to their social system. These animals live in colonies of several dozen to several hundred individuals. Only one dominant female, the queen, can reproduce.

“Unlike bees or ants, a female is not born a queen,” explains Brieño-Enríquez. – When a queen dies or is removed from the colony, subordinate females compete to take her place, and the one who wins becomes reproductively active. Any girl can become a queen.

To learn more about this process, the researchers removed 3-year-old females from the colony to induce the naked moles to become reproductively activated. Then they compared the new queens with the subordinates. As it turned out, the non-reproducing females had the right cells in their ovaries, but they didn’t start dividing until after they had turned into queens.

Scientists hope that their research will contribute to a better understanding of fertility problems in other mammals, including humans. Brieño-Enríquez adds, “Ovarian health affects cancer risk, heart health and even life expectancy. Understanding it better can help us find ways to improve our health.”

Main photo source: Adobe Stock

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