The battle of the sexes (210.3)

Although genetic sex is determined at fertilization, the decision to differentiate as a male or female occurs within the bipotential gonad during fetal life. Somatic progenitor cells in XX and XY mouse gonads are “primed” to differentiate along either the male or female pathway. At the bipotential stage, both XX and XY cells express very similar levels of genes associated with both ovary and testis development. The expression of the Y-linked male sex-determining gene (Sry) in XY gonads leads to both activation of male pathway genes, and repression of female pathway genes. Work using mutant and transgenic mice suggests that failure to suppress the female pathway is critical to establish male (testis) development. Bifurcation of organ fate begins between E11.0-E12.0 in mice and involves a dynamic transcription network that is poorly understood. We profiled the XX and XY gonad transcriptomes at fine granularity during this period and conducted a DNase Hypersensitivity study to define promoters and enhancers....