Biologists have figured out why the fertility of naked mole rats does not decrease with age. Reported by the University of Pittsburgh.
Naked mole rats are underground-dwelling rodents that resemble a bald fat rat. Tiny eyes and poor vision, but almost never cancerous, they feel no pain in many species, living in underground colonies where only a queen can have offspring. At the same time, the uterus never stops bearing children, and their fertility only increases with age. In most mammals, including humans and mice, females are born with a limited number of eggs produced in the womb through oogenesis. As this egg supply is depleted over time – some are released during ovulation, but many simply die – fertility declines with age.
The researchers compared the ovaries of naked mole rats and mice at different developmental stages. Despite their similar size, mice live no more than four years and begin to show a decline in fertility by nine months, while naked mole rats live for 30 years or more.
They found that female naked mole rats had an exceptionally large number of eggs compared to mice, and the death rate of these cells was lower than in mice. For example, an 8-day-old female naked mole rat has an average of 1.5 million eggs, which is about 95 times more than mice of the same age.
Most importantly, oogenesis occurs in naked mole rats after birth. This type of progenitor cells was actively dividing in 3-month-old animals and was also found in 10-year-old animals, suggesting that oogenesis may continue throughout their lives.
This discovery could refute the dogma that female mammals can produce only a limited number of eggs.
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