part_of starts_at ends_at urogenital sinus caudal urogenital sinus epithelium epithelium of pelvic urethra urogenital sinus ridge sinus ridge The urogenital sinus ridge (UGS ridge) (syn: sinus ridge) (TS:19-TS:22) is part of the urogenital sinus (TS:19-TS:21), and part of the caudal urogenital sinus (TS:19-TS:20), then part of pelvic urethra (TS:21-TS:22). The thickened and raised, dorsal portion of the urogenital sinus or epithelium of pelvic urethra located at the site where the common nephric duct/nephric duct or reproductive ducts join the urogenital sinus/pelvic urethra. From TS:19-TS:22 the urogenital sinus ridge surrounds the common nephric duct. Marked by Cdh1 (E-cadherin) and derived from cloacal endoderm. It is a signalling centre, important for regulating common nephric duct remodelling and apoptosis during ureter maturation and repositioning, and later in development, may be a source of inductive signals regulating vaginal outgrowth. At TS:23, it becomes the urogenital sinus ridge of male/female and is part of the pelvic urethra of male/female. At TS:24, it becomes the verumontanum in males and sinovaginal bulb in females, the protrusion of the pelvic urethra where the reproductive ducts join. anatomical_structure EMAPA:36099 TS19 TS22