Transcriptome and chromatin accessiblity analysis of Gli1+ and Amhr2+ mesenchymes in the fetal murine reproductive tracts

Precursors for the male and female reproductive tracts (also known as the Wolffian duct and the Müllerian duct) co-exist in a mammalian embryo before sexual differentiation. The Wolffian duct and Müllerian duct are surrounded by their own mesenchymes in the mesonephros, which can be distinguished by their specific expression of Gli1 and Amhr2, respectively. In the XX embryo, during sexual differentiation, the Wolffian duct degenerates. In this study, by tracking the fate of the Gli1+ Wolffian duct mesenchyme in the tamoxifen inducible genetic lineage tracing model Gli1-CreER; Rosa-Tomato, we demonstrate that the Wolffian duct mesenchyme does not regress along with the Wolffian duct epithelium in the XX embryo. Instead, the Wolffian duct mesenchyme is repurposed and becomes a unique mesenchymal population in the female reproductive tract. Profiling the transcriptomes and chromatin accessibilities of the Gli1+ Wolffian duct mesenchyme in XX and XY during sexual differentiation (E14.5 and E16.5) shows signaling pathways and transcriptional factors that potentially involves the female and male fate differentiation of the Gli1+ Wolffian duct mesenchyme. Comparing the transcriptomes between the Gli1+ Wolffian duct mesenchyme and the Amhr2+ Müllerian duct mesenchyme from the neonatal uterus reveals similarities and differences between the two mesenchymal populations in the female reproductive tract. Ex vivo ablation of the Wolffian duct mesenchyme stunted the growth of the fetal female reproductive tract. In summary, our discovery of the contribution of the Wolffian duct mesenchyme to the female reproductive tract provides new insights into our understanding of sexual differentiation of reproductive tracts. Overall design: RNA-seq and ATAC-seq on sorted Gli1+ mesenchymal cells from XX and XY mesonpehroi on E14.5 and E16.5; and RNA-seq of sorted Gli1+ and Amhr2+ mesenchymes on neontal uteri