Crucial roles of the mesenchymal androgen receptor in Wolffian duct development

Wolffian duct maintenance and differentiation is predominantly driven by the androgen action, which is mediated by the androgen receptor (AR). It is well established that the mesenchyme indicates the fate and differentiation of epithelial cells. However, in vivo developmental requirement of mesenchymal AR in Wolffian duct development is still undefined. By designing a mesenchyme-specific Ar knockout (ARcKO), we discovered that the loss of mesenchymal Ar led to the bilateral or unilateral degeneration of caudal Wolffian ducts and cystic formation at the cranial Wolffian ducts. Ex vivo culture of ARcKO Wolffian ducts invariably resulted in bilateral defects, suggesting that some factor(s) originating from surrounding tissues in vivo might promote Wolffian duct survival and growth even in the absence of mesenchymal Ar. Mechanistically, we found cell proliferation was significantly reduced in both epithelial and mesenchymal compartments; but cell apoptosis was not affected. Transcriptomic a..., , , # Crucial roles of the mesenchymal androgen receptor in Wolffian duct development

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## Description of the data and file structure

**Supplementary figure 1. Coiling of the contralateral epididymis was decreased in ARcKO male embryos with the unilateral cystic epididymis**. (A) Brightfield images of PND0 epididymides of the control and ARcKO groups. Regions outlined by dashed lines were enlarged for illustrating measurement of the number of turns. (B) Quantification of the average number of turns per 1 mm. Results were shown as mean ± SD and analyzed by two-tailed unpaired Student’s t-test. N=5 for control group, N=4 for ARcKO group.

**Supplementary figure 2. Immunohistochemical staining of AR in PND0 epididymides from control, unaffected side of ARcKO, and affected side of ARcKO embryos.**

**Supplementary figure 3. Characterization of Osr2Cre+; Rosa26tdTomato+.** (A) Whole mount immunofl...