A study carried out by a team of researchers from Eugin’s Basic Research Laboratory, headquartered in the Barcelona Science Park, reveals that the quality of human eggs is directly connected to the regulation of the cell mitochondrial activity, which is the part responsible for supplying most of the energy necessary for cell activity. The results of the work – published in the journal Molecular Reproduction & Development – open a new way  to provide answers to fertility problems derived from delayed maternity.

Eugin’s team of scientists has developed a comparison between eggs at different stages of maturation. In this sense, not only genes have been analysed, but also their isoforms (which are present in oocytes), pointing to the regulation of mitochondrial activity as one of the relevant mechanisms when obtaining an ovum from quality.

The mitochondria of the ovules play a very important role during the reproductive process, either naturally or through in vitro fertilization techniques, for several reasons. On the one hand, throughout the reproductive process (from the maturation of the ovules, through fertilization and early embryonic development), a correct energy supply is required, provided mainly by the mitochondria. On the other hand, it is necessary to take into account that the ovum is the provider of the mitochondrial content of the future offspring.

“Therefore, a correct mitochondrial load in the ovum, both in number and in function, is decisive for a correct embryonic and fetal development”, says Rita Vassena, scientific director of Eugin.

Advances such as those in this study represent new avenues of research to provide answers to fertility problems derived, on many occasions, from delayed motherhood. In recent decades, the average age in Spain in which women have their first child has increased to 32 years (25 years in 1980). However, after the age of 35, the reproductive potential of a woman’s eggs decreases rapidly.

“Despite the vast amount of research carried out, the essential determinants that are established during egg maturation are still unknown, so this knowledge helps us establish appropriate methodologies to select the highest quality eggs,” says Vassena.

» Reference article: Cornet-Bartolomé D, Barragán M, Zambelli F, et al. Human oocyte meiotic maturation is associated with a specific profile of alternatively spliced transcript isoforms. Mol Reprod Dev. 2021;88(9):605-617. doi:10.1002/mrd.23526

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