The structure of the mucosal folds within the pancreaticobiliary junction

Abstract

BACKGROUND: This investigation concerns a structure within the pancreaticoduodenal region of the body, known as the pancreaticobiliary junction (PBJ), which is formed from the convergence of the terminal common bile and main pancreatic ducts. Certain components of this junction such as the sphincter of Oddi have been well documented within the literature, but surprisingly little is known about the folds that line the mucosa in this region. These structures are understood to prevent reflux of duodenal content, but whether this is achieved through an active rather than purely passive mechanism has yet to be determined. AIMS: The principal aim of this study was to investigate the distribution and length of the mucosal folds within the terminal bile and pancreatic ducts. A secondary aim was to identify features within the folds that are consistent with an active function, including smooth muscle, innervation and hormonal receptors. METHODS: PBJ specimens from 10 human cadavers (five male, 66-90 years old) were embedded in paraffin and sectioned transversely (3-4 μm thickness) at 200 μm intervals, beginning at the major duodenal papilla. These sections were stained with hematoxylin and eosin, and immunohistochemically with anti-actin, anti-S100, and anti-cholecystokinin A for detection of smooth muscle actin, innervation, and cholecystokinin A receptors, respectively. Three surgical specimens (2 male, 63-72 years old) were also evaluated. ImageJ software was used to measure mean fold length and distribution, as well as the relative distribution of S100 and the density of smooth muscle actin staining within the folds of the terminal bile and pancreatic ducts. The morphology of the folds was also examined in one additional specimen under scanning electron microscopy.