Ms Adela Tashkent

Honours thesis

Modelling Oxygen Consumption: A Valuable Tool in Reproductive Biology

Over the last two years, the University of Adelaide's Research Centre for Reproductive Health has been successful in winning prestigious research grants to investigate alternative assisted reproduction techniques. With infertility affecting around 1 in 6 couples, and predicted to increase to 1 in 3 couples over the next decade, this investment of time and money comes at no better time. An innovative alternative to the well established assisted reproduction technique of in vitro fertilisation (IVF) is in vitro maturation (IVM). IVM reduces the need for hormone injections, namely gonadotrophins - used to stimulate the ovary - making it a far more cost effective and safe treatment. In particular, IVM gives hope to women suffering from Polycystic Ovarian Syndrome, for whom IVF is unsuitable. For both IVF and IVM, where embryos and oocytes (eggs) are cultured in the lab, that is in vitro, it is vital that conditions in the lab closely match those in utero. One such condition of great importance is the supply of oxygen. Oxygen consumption is indicative of an embryo's (and most probably an oocyte's) metabolic activity and plays a key role in determining embryo quality (Lopes et al. 2005). In assisted reproduction techniques it is important to select strong and healthy embryos for implantation for the best chance of success. It is essential then for researchers to better understand oxygen consumption rates of embryos to ensure there is adequate supply of oxygen in the culture medium. In this thesis we will consider mathematical models needed to determine oxygen consumption rates of embryos and oocytes from data yielded by an experimental assay presented in Houghton et al. (1996). In that paper the assay is used to determine oxygen consumption rates of murine (mouse) embryos and some experimental data is given which we will make use of. The assay has also been used in the University of Adelaide's Research Centre for Reproductive Health up to the present time for measuring oxygen consumption rates of oocytes and some experimental data has been provided to us. The experiment and the modelling attempt presented in Houghton et al. (1996) is discussed in Chapter 2 of this thesis. This is followed in Chapter 3 by a formulation of a mathematical model applicable to the experimental data supplied in Houghton et al. (1996). Application of the model to that data is considered in Chapter 4. In Chapter 5 we adapt our model for the experiment conducted by the Research Centre for Reproductive Health to determine the oxygen consumption rate of bovine (cow) oocytes. In Chapter 6 we summarise the ?ndings of this thesis and discuss where further investigation may be useful. Of particular interest to us is the rate at which embryos and oocytes consume oxygen and how we incorporate this into our mathematical model.