Women and female mammals are born with a predetermined number of eggs. When these are exhausted, their reproductive life ends. Naked mole rats, however, are an exception, as they appear to have eternal fertility, allowing them to reproduce throughout their long lives. A new study, published Tuesday in Nature Communications, sheds light on this extraordinary ability. The findings could help find new therapies for human fertility problems. "Naked mole rats (Heterocephalus glaber) are the strangest mammals," says Miguel Brieño-Enríquez of the University of Pittsburgh School of Medicine. "They are the longest-lived rodent, they almost never get cancer, they don't feel pain like other mammals, they live in underground colonies, and only the queen can have babies. But for me, the most surprising thing is that they never stop having babies; they don't have a drop in fertility as they age. We want to understand how they do this," he explains. Researchers believe that the mole rat queen's ability to reproduce into old age suggests special processes to preserve her ovarian reserve and prevent fertility decline. "There are three possibilities for how they do this: they're born with lots of eggs, not as many of these eggs die, or they continue to create more eggs after birth," Brieño-Enríquez notes. "My favorite hypothesis is that they use a cocktail of all three," she says. Related News Standard Valentine's Day No. Five Sex Lessons We Learned From Animals in the Last Year J. de J. Skipping sleep to do it until you're exhausted, butting your head (and elongating your neck in the process), or drinking urine beforehand... these may not be very recommendable practices, but who's to judge 'love'? And if you're an incel, there's someone much worse than you here. Indeed, Brieño-Enríquez and her collaborators found evidence for each of the three processes. The researchers compared ovaries from naked mole rats and mice at different stages of development. Despite their similar sizes, mice live a maximum of four years and begin to show a drop in fertility at nine months, while naked mole-rats have a lifespan of 30 years or more. They found that female naked mole-rats have an exceptionally high number of eggs compared to mice and that the mortality rates of these cells were lower. For example, at 8 days old, a female naked mole-rat has an average of 1.5 million eggs, about 95 times more than mice of the same age. Most notably, the team found that oogenesis occurs after birth in naked mole-rats. Egg precursor cells were actively dividing in 3-month-old animals, and these precursors were found in 10-year-old animals, suggesting that oogenesis could continue throughout their lives. “This finding is extraordinary,” says lead author Ned Place of Cornell University’s College of Veterinary Medicine. “It challenges the dogma established almost 70 years ago, which stated that female mammals are endowed with a finite number of eggs before or shortly after birth, with no additions to the ovarian pool occurring thereafter.” Naked mole-rats live in colonies of several dozen to hundreds of individuals. Like bees or ants, colony members divide up tasks, including defense, tunneling, caring for young, and gathering food. Only the single dominant female in a colony can reproduce, and she suppresses reproduction in other females to maintain her queen status. “Unlike bees or ants, a female naked mole-rat is not born a queen,” Brieño-Enríquez explained. “When the queen dies or is removed from the colony, subordinate females compete to take her place and become reproductively active. Any female can become queen.” Transition to Queenhood To learn more about this process, the researchers removed 3-year-old females from the colony to accelerate reproductive activation and compared these new queens with subordinate females. They found that the non-reproductive subordinates had egg precursor cells in their ovaries, but the cells began dividing only after a transition to queenhood. “This is important because if we can figure out how they can do this, we could develop new drug targets or techniques to help human health,” Brieño-Enríquez says. “Even though humans live longer, menopause still occurs at the same age. We hope to use what we are learning from the naked mole rat to protect ovarian function later in life and prolong fertility,” she adds. MORE INFORMATION news If They manage, for the first time, to reverse the direction of time in a real quantum system news No Ten years of Chelyabinsk, the unexpected asteroid According to the researcher, "the ovary is more than just a baby factory." Ovarian health "influences cancer risk, heart health, and even lifespan. A better understanding of the ovary could help us find ways to improve overall health."
