It is clear why the 'oocytes' that are the source of eggs do not age for decades


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The cells that make up the human body divide using DNA as a blueprint to create new cells. Cells usually have a lifespan of weeks to months, or even years at the longest, and at the end of their lifespan, they stop dividing and stop functioning. However, the oocytes that give rise to female eggs are stored in the ovaries for decades and produce eggs on a regular basis. The Center for Genomic Regulation , a Spanish research institute, has published a paper on why oocytes live for decades.

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About 6 to 7 million oocytes are produced at the time of the fetus, and the number decreases to about 1 to 2 million by the time of birth. By the time puberty is reached, the number will decrease to about 300,000 and no new ones will be made. Some of the oocytes in the body undergo two divisions to mature into an egg with 23 chromosomes and are excreted in the monthly menstrual cycle. Therefore, of the 300,000 oocytes, only a few hundred mature into eggs.


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Oocytes are limited in number because they are not newly created after birth. Therefore, it is difficult to study because precious oocytes must be extracted from the female ovary in order to study.

The Center for Genomic Regulation research team used the ovaries of women aged 19 to 34 years who underwent ovariectomy and the ovaries of mice and frogs. As a result, it became clear that the mitochondria of oocytes have different metabolic pathways from those of other animal cells.

Mitochondria are organelles that metabolize energy from sugar using enzymes, and at the end of metabolism, they activate a reaction system called the electron transport chain. According to the research team, a set of proteins and enzymes called 'complex I', which controls the first stage of the mitochondrial electron transport chain, was found to be almost inactive or absent in oocytes.

In fact, active oxygen is produced as a by-product of this complex I, and it is thought that this active oxygen damages cells. The researchers suggest that the lack of metabolism in complex I in oocytes may help them survive for decades without being damaged. According to the research team, the only cells other than human oocytes that are known to live long due to the inactivity or absence of complex I are the cells of the parasitic plant mistletoe .

Elvan Böke, a researcher at the Center for Genomic Regulation and a senior author of the treatise, said, 'Inhibitors of mitochondrial complex I have been proposed for cancer treatment. This inhibitor is promising for future research. If so, it may be possible to target cancer cells while preserving egg matrix cells. ' 'One in four cases of female infertility is unexplained and we still don't understand much about female reproduction. We have oocytes that have been healthy for decades. I would like to discover a strategy to maintain this and find out why the oocyte strategy fails in old age. '

in Science, Posted by log1i_yk