abnormal urinary system development abnormal ureteric bud morphology MP:0006032 MPheno.ontology abnormal UB morphology abnormal mesonephric diverticulum morphology any structural anomaly of the epithelial swelling on the metanephric duct that elongates to invade the adjacent metanephric mesenchyme; interactions between the ureteric bud and the metanephric mesenchyme leads to the initiation of outgrowth and repetitive branching of the UB that ultimately generates the definitive renal collecting system and induces formation of renal vesicles from the mesenchyme tissue