Assertion: alimentary canal's layer | /r/CapableOf | thicken in place
Facets:
value: along the tract
type: LOCATION
value: to form sphincters
type: PURPOSE
Source sentences:
text: In some places, the circular layer thickens to form sphincters that act as valves to prevent the backflow of food from one organ to the next.
text: In several places along the tract, the circular layer thickens and forms sphincters that act as valves that control food passage from one organ to the next, they also prevent backflow.