Biologists have figured out why the fertility of naked mole rats does not decrease with age. It is reported by the University of Pittsburgh .
Naked mole rats are rodents living underground, resembling a bald fat rat. Tiny eyes and poor eyesight, but they almost never get cancer, do not feel many types of pain, live in underground colonies where only a queen can have cubs. At the same time, the uterus never stops giving birth to children, and with age, their fertility only increases. In most mammals, including humans and mice, females are born with a finite number of eggs, which are produced in utero through oogenesis. Because this supply of eggs is depleted over time—some are released at ovulation, but most simply die—fertility declines with age.
The researchers compared the ovaries of naked mole rats and mice at different stages of development. 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 have a lifespan of 30 years or more.
They found that female naked mole rats had an exceptionally large number of eggs compared to mice, and that the mortality rate of these cells was lower than that of mice. For example, at the age of 8 days, the female naked mole rat has an average of 1.5 million eggs, which is about 95 times more than in mice of the same age.
Most notably, oogenesis occurs in naked mole rats after birth. Progenitor cells of this type were actively dividing in 3-month-old animals and were also found in 10-year-old animals, suggesting that oogenesis can continue throughout their life.
This discovery may disprove the dogma that female mammals can only produce a limited number of eggs.
Earlier, Yakut scientists conducted an autopsy of the carcass of an ancient bear aged 3,460 years.