Control of reproductive function

• Main Author: Webb, Robert
• Published: University of Edinburgh 2012
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.735476

My research has focused on the control of reproductive function, particularly ovarian function in farm animal species. It has included the study of the mechanisms controlling follicular growth, ovulation rate control and corpus luteum function. Experimental approaches have included comparisons between mono- and poly-ovular species, between breeds of sheep with differing ovulation rates and utilising genetically selected lines of sheep. The work has included the development of a novel ovarian transplantation approach in large animal species for maintaining fertility after low temperature freezing. As well as providing an excellent large animal model to study the recruitment of primordial follicles and follicle development to ovulation, it is currently being extended to the development of whole ovary cryopreservation and transplantation. The research has involved the delineation of the importance and roles of gonadotrophins, metabolic hormones and locally-produced growth factors in follicular growth and development. The results demonstrated the interaction between extraovarian hormones and intra-ovarian growth factors, including the importance of growth hormone and related hormones and growth factors on follicular development. These studies required the development and detailed validation of a range of hormone assays and physiologically relevant cell culture systems for follicular cells. The importance of environmental factors, such as nutrition, was investigated. This included the demonstration of the direct effects of nutrition on gene expression within follicular cells to influence oocyte quality and embryo survival. Subsequent work investigated the underlying mechanisms of action, demonstrating the differing impact of various metabolic factors necessary for either follicular growth or the maintenance of oocyte quality. This research enabled the formulation of diets and feeding strategies that significantly improved pregnancy rates in dairy cattle and which are now being used by the industry. This work is of particular relevance in halting the decline in fertility, since selection of dairy cows on the single trait of milk production was shown to result in a continuing reduction in conception rates at approximately 1% per annum.