Biomechanical properties of the capsule and extracellular matrix play a major role during the Wolffian/epididymal duct development

This study investigated how the biomechanical properties of the capsule and surrounding mesenchyme/extracellular matrix regulate the morphogenesis of the Wolffian duct—the embryonic precursor of the epididymis. Using a developmental series, the authors measured bulk/structural stiffness of the capsule and underlying ECM to understand how tissue mechanics contribute to duct elongation and coiling, processes essential for proper epididymal and male reproductive development. Structural stiffness remained largely constant across stages, with a notable late-stage increase in capsule stiffness likely driven by compression of the ECM against the capsule during duct coiling. Membrane-tension imaging revealed spatially variable lipid tension among mesenchymal cells along the duct, suggesting dynamic cellular responses that help maintain stiffness homeostasis. Loss of Ptk7—a known regulator of ECM integrity—resulted in increased stiffness at E18.5, consistent with impaired ECM organization. Collectively, the findings highlight that mechanical properties of the encapsulating tissues are integral to normal Wolffian duct morphogenesis.