part_of starts_at ends_at genitourinary system nephric duct mesonephric duct EMAPA:16577 Wolffian duct anatomical_structure EMAPA:28429 EMAPA:28425 The nephric duct (nd) (syn: mesonephric duct, Wolffian duct) (TS:14-TS:24). Paired epithelial ducts which develop early in development (TS:14) in the cranial/anterior intermediate mesoderm and extend caudally down the rostro-caudal axis of the embryo to terminate at the cloaca. The nephric duct is subdivided along its anterior-posterior length, into the pronephric portion, mesonephric portion (part of the mesonephros) (located in mesonephros, anterior), metanephric portion (adjacent to the metanephros) and common nephric duct (posterior portion below the metanephros). These regions are stage-dependant, with the pronephric portion present at TS:14 in the pronephros, the mesonpehric portion from TS:15 in the mesonephros and posterior to these, the metanerphric portion from TS:17. The regions are part of either the urinary or reproductive system. After the urogenital sinus extends from the cloaca, the nephric duct connects to the dorsal side of the caudal urogenital sinus at the urogenital sinus ridge. The ducts are marked by Cdh1 and Hoxb7. As the ontology becomes gender-specific, the nephric duct becomes the nephric duct of male/female (from TS:20). TS14 TS24