Assertion: ureter's muscle layer | /r/HasProperty | prevented
Facets:
Source sentences:
text: Essentially, the ureters are passageways that carry urine from the kidneys to the bladder through contraction of the smooth muscle layers in their walls that propel urine into the bladder by peristalsis and is prevented from flowing back by small valve-like folds of bladder mucosa that flap over the ureter openings.