DMRT1 is required for Mullerian duct formation in the chicken embryo

DMRT1 is a conserved transcription factor with a central role in gonadal sex differentiation. In all vertebrates studied, DMRT1 plays an essential function in testis development and/or maintenance. No studies have reported a role for DMRT1 outside the gonads. Here, we show that DMRT1 is expressed in the paired Mfillerian ducts in the chicken embryo, where it is required for duct formation. DMRT1 mRNA and protein are expressed in the early forming Mfillerian ridge, and in cells undergoing an epithelial to mesenchyme transition during duct morphogenesis. RNAi-mediated knockdown of DMRT1 in ovo causes a greatly reduced mesenchymal layer, which blocks caudal extension of the duct luminal epithelium. Critical markers of Mfillerian duct formation in mammals, Pax2 in the duct epithelium and Wnt4 in the mesenchyme, are conserved in chicken and their expression disrupted in DMRT1 knockdown 'ducts. We conclude that DMRT1 is required for the early steps of Mfillerian duct development. DMRT1 regulates Mfillerian ridge and mesenchyme formation and its loss blocks caudal extension of the duct. While DMRT1 plays an important role during testis development and maintenance in many vertebrate species, this is the first report showing a requirement for DMRT1 in Mullerian duct development. (C) 2015 Elsevier Inc. All rights reserved.