[Is the duodenal papilla an autonomic sphincter? A contribution to the functional morphology (author's transl)].

A morphologic study of the duodenal papilla was performed by laminations in three planes. The muscle system reveals that there are no autonomic sphincters, but muscle bundles deriving from duodenal longitudinal and circular muscle layers, interdigitating and acting for opening of the papillary mouth. Activity results from myogenous rhythmic contractions of smooth muscle cells, stimulated by the ductal hydrostatic pressure, and from the duodenal peristalsis. The closure of the papilla is weak, incomplete and achieved by the oblique entrance of the duct. Interpretation of functional analysis and procedures of treatment should be based upon the knowledge of normal morphology of the papilla.