Age is one of the factors that influence the capacity to procreate. Researchers at the University of Montreal Hospital Research Center (CRCHUM) examined the genetic bases connected to this problem in women. They have thus found a new possible explanation.
The oocytes are the female reproductive cells before being fertilized and develop into ova. Women have a specific number, which over the years goes down. As the body ages, moreover, the quality of the remaining eggs diminishes. All this makes it much harder natural conception after 37 years of age.
Canadian researchers examined the genetic causes of oocyte cell. They identified errors in chromosome segregation, splitting pairs of alleles during the formation of germ cells. Errors cause oocytes with abnormal numbers of chromosomes, resulting in difficulty in conceiving.
The most likely explanation for the increase of chromosomal abnormalities is a malfunction of cohesin. It is a protein complex that holds together the chromosomes. According to many scholars, with age the cohesin deteriorates and the chromosomes lose cohesion. Canadian researchers have expanded this theory.
Microtubules are cylindrical structures internal to the cells, responsible for cell movement. When the cell prepares for division, the chromosomes unite around the helical structure and select them. After the division, they send the chromosomes to opposite ends of the nucleus of the daughter cells, precisely causing segregation.
The Canadian study shows that 50% of the eggs of older mice have dysfunctional microtubules. The problem therefore is not the age of the core, as that of the oocyte in its entirety. By placing a young nucleus into an oocyte old, in fact, the problems remain. The finding also applies to human women and could open the door to new methods to rejuvenate the eggs. During pregnancy it is important to undergo controls and prenatal screening tests: with such fetal DNA test, the mother can know if the fetus is affected by chromosomal abnormalities.