As the first in the world, researchers from Aarhus University have found the molecular movements that take place in the very earliest eggs in the woman’s ovaries. In the long term, this discovery could help childless women who, despite fertility treatments, cannot become pregnant.

2017.11.02 | Helle Horskjær Hansen

As the first in the world, researchers from Aarhus University have found the molecular movements that take place in the very earliest eggs in the woman’s ovaries. Foto: Colourbox.

A twenty-year-old woman has a 34 per cent chance of becoming pregnant per month. When she reaches the age of forty, the chance is six per cent. That is, if she has sex twice a week. A new study from Aarhus University now shows how the egg reserve can be impacted by injecting substances directly into the woman’s ovaries and thereby activating the earliest eggs. In the long term, this can lead to the woman becoming pregnant with her own eggs. 

"This is the first time we have succeeded in getting a resolution where we can distinguish between the very earliest egg stages. When you inject directly into the ovaries, it is important that you do not affect the entire organism with side effects to follow, and this is why the discovery is important. We are now able to isolate individual cells and use technology that enables us to see what the individual stages consist of," says one of the researchers behind the study, Emil Hagen Ernst from the Department of Biomedicine at Aarhus University.

The results have been published in Human Reproduction.

Women activate around twenty eggs each month. The entire reserve of eggs lies dormant until they are activated and compete to become the 'winner' – the egg that is matured and eventually conceived. Each month prior to ovulation, women of childbearing age develop follicles, also known as egg blisters. The egg grows within these follicles and during ovulation the follicle ruptures, before the egg is picked up by the oviduct.

"Many of the factors we have identified have not previously been linked to the activation/dormancy of eggs. In the long term, we therefore have the opportunity to test substances that are involved in the dormancy/activation of the as yet undeveloped egg that is encapsulated in follicles," explains Karin Lykke-Hartmann from the Department of Biomedicine at Aarhus University. She is also a member of the research group.  

The fact that researchers can distinguish with great precision between the earliest stages of the egg is precisely what makes it possible to either activate or stop the activation of eggs in a targeted way. This may, for example, benefit women who lose their egg reserves early for genetic reasons.  

"At present, all infertile women receive the same treatment, that is with a substance that is directed towards the later stages of the egg maturing. We do not presently have any means of activating the 'dormant' eggs. Now we have new knowledge about which genes are present and in the long term, this will tell us what we should direct new medicine towards to activate these dormant eggs. This will be able to help the millions of women around the world who cannot have children despite countless treatments at fertility clinics," explains Karin Lykke-Hartmann. 

Background for the results: 

The study is basic research. 

Partners: The project was carried out in collaboration with Rigshospitalet, Imperial College London, Aarhus University Hospital, Herlev Fertility Clinic and the Bioinformatics Research Centre, Aarhus University.

The project was carried out with support from the Aarhus University Research Foundation (AUFF), The King Christian X Foundation, Th. Maigaards Eft. Fru Lily Benthine Lunds Foundation and the Foundation for the Promotion of the Health Sciences.

Read the article Dormancy and activation of human oocytes from primordial and primary follicles: molecular clues to oocyte regulation

Contact 

PhD, DMSc Emil Hagen Ernst
Aarhus University, Department of Biomedicine
Tel.:(+45) 8716 7258
ehernst@biomed.au.dk

Associate Professor, PhD Karin Lykke-Hartmann
Aarhus University, Department of Biomedicine
Tel.: (+45) 2939 0558
kly@biomed.au.dk