How a passion for numbers is assisting fertility

Wednesday, 29 March 2006

A collaborative effort between the Research Centre for Reproductive Health (RCRH) and the Faculty of Engineering, Computer and Mathematical Sciences at the University of Adelaide is using mathematical modelling to uncover the complex world of egg maturation.

The RCRH embryology research group led by Associate Professor Jeremy Thompson is being aided by mathematical modelling and computer systems to predict the exact levels of nutrients needed by the maturing egg in vitro to ensure a higher success rate of embryo development. This sophisticated collaborative effort has already changed the design of some RCRH embryology laboratory practices.

Alys Clark is a PhD student in the Faculty of Engineering, Computer and Mathematical Sciences who is working with RCRH researchers to recreate the precise complex nutrient formula naturally found in the fluid surrounding the maturing egg. Her PhD supervisors are Dr Yvonne Stokes and Dr Stephen Cox, both from the School of Mathematical Sciences.

To unravel the complex nutrient base Ms Clark is constructing mathematical models and solving the resulting systems of equations using computational techniques. The RCRH research team aims to recreate the delicate natural maturing egg nutrient solution and environment to ensure a higher success rate through in vitro fertilisation.

Growing and maturing eggs, also known as oocytes, are surrounded by a group of specialised cells called cumulus cells that exist to facilitate the growth, maturation and delivery of the egg to the reproductive tract where it can then be fertilized. A key function of cumulus cells is to regulate the nutrition of the egg from the surrounding fluids that bathe the cumulus-egg structure.

Associate Professor Jeremy Thompson said: "The eggs appear to be very sensitive to the concentration of certain energy substrates, so delivering the right amount of substrate is crucial for normal egg growth and maturation. However, when surrounded by cumulus cells, understanding what actually reaches the egg is very difficult to estimate without sophisticated and specialised help."

Ms Clark has been using different mathematical modelling strategies to determine the levels of nutrients reaching the surface of the egg from the surrounding fluid via the cumulus cells.

Already her work has changed the design of RCRH experiments, where the level of oxygen used to investigate its effect during egg maturation was much lower than normally considered optimal, with the result that this has affected subsequent embryo development.

The clinical outcome from this collaborative effort suggests that eggs in the follicle of an ovary respond to oxygen concentration and therefore adapt to different levels.

The relevance of this lies with changes in fertility because of lifestyle factors such as smoking, exercise and obesity, which may cause reduced ovarian blood supply, and potentially affect women's natural fertility rates.

The RCRH embryology group is conducting further studies into the recent egg nutrient transfer findings.

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