ESPE Abstracts

There is no single conception of sex that covers the multitude of biological process that are commonly encompassed by the term and its cognates. Gonadal sex determination is sometimes known as 'primary' sex determination due to its centrality in our understanding of 'maleness' and 'femaleness'. In mammals, this is characterised by the sexually dimorphic development of an initially bipotential gonadal primordium in the fetus into either a testis or an ovary. The development of a testis most commonly requires the expression of SRYfrom the Y chromosome in order to initiate a cascade of gene expression, much of which functions to opposethe influence of pro-ovary signals. If SRYexpression is disrupted, varying degrees of XY gonadal sex reversal are observed, with attendant consequences for the phenotypic sex of the individual. Mutual antagonism between the pro-testis and pro-ovary pathways is found at the heart of the sex-determining mechanism. I will discuss recent advances in our understanding of the cellular and molecular basis of this so-called 'battle of the sexes' during gonad development, with an emphasis on signalling pathways required for testis determination in mice and humans.