Current Research Current Research Collaboration with Professor Tony Payne, Drs Des Gilmore and Suzanne Ullmann. A person's sex is determined by their genes, but during development hormones are also important. Initially, reproductive organs in both sexes are structually identical, though in most mammals sex differentiation occurs before birth. A gene on the Y chromosome causes testes to develop and produce hormones which control further masculinization.
Feminization is essentially the default mode of development.
However, in marsupial mammals young are born at an underdeveloped stage and sex differentiation may occur after birth. Moreover, both sexes may retain structures which are normally sex-specific in other mammals. We work on the South American opossum as its young are accessible at a very early stage and sex differentiation occurs around the time of birth. We are particularly interested in determing the role of gondal steriod hormones by discovering how structural differentiation of the reproductive system is related in time to the appearance of hormones and their receptors in target tissues. The issue is of considerable topical importance since the realisation that environmental contaminants produce asymmetric sex ratios and sex abnormalities in may vertebrates.