The Ampulla of Vater. 173 



At the point where the ducts penetrate the muscular coat, 

 the latter is decidedly thickened. The longitudinal layer parts, 

 allowing the ducts to pass between its fibers, and on the side 

 of the ductus choledochus, the thickening of the muscular 

 layer is due to an addition of special fibers to this layer These 

 fibers interlace in a most complex manner, and extend as a 

 tapering bond along the pyloric side of the ductus choledo- 

 chus nearly to its orifice. On the side of the duct of 

 Wirsung no such process of fibers is sent along that duct. The 

 circular layer, however, is much thickened on this side, and 

 abuts squarely against the duct. On the opposite side it curves, 

 following the direction of the ductus choledochus. It tapers 

 toward the extremity, but ends somewhat abruptly (PI. XIV., 

 Fig. I, d, e). The wedge of muscular fibers between the ducts 

 is made up partly of longitudinal, and partly of circular fibers. 



Fig. 3. The same as 2, except that the ductus choledochus is prolonged nearly 

 to the orifice of the ampulla. This is of rare occurrence. 



Fig. 4. Section made at right angles to Fig. I, to show the ducts and ampulla 

 in cross section. Stained in picrocarmine. The duct of Wirsung previously in- 

 jected with Berlin blue. X 15. 



h. Transverse section of the ductus choledochus, which is enclosed by a dotted 

 line. Its lumen is divided into compartments by the anastomosing processes seen 

 in Fig. I. 



i. Duct of Wirsung also surrounded by a dotted line, and divided into com- 

 partments. The dotted line is double at the left of the figure, as the exact limit 

 of the duct could not be determined. 



e, d. Plain muscular fibers, partly surrounding the ampulla and ducts on the 

 side toward the pylorus. 



g. All the interior not surrounded by the dotted lines belongs to the ampulla, 

 and is greatly divided by folds and processes. 



Fig. 5. Magnified 20 diameters, stained in hgematoxylin. Section like the pre- 

 ceding, but nearer the aperture of the ampulla. This figure is given to show the 

 exceeding complexity and sieve-like division of the ampulla by its anastomosing 

 folds and processes. 



d, and e. The thin edge of the muscular coats prolonged toward the summit of 

 the ampulla. 



Fig. 6. Longitudinal section of a single minute process, like that near g, fig. 5 ; 

 stained in hsematoxylin. Many simple glands dip down into the surface: they are 

 merely depressions, for their epithelium is identical with that covering the general 

 surface of the process, x 250. 



7ti. A glandular depression becoming double, 



n. Simple glandular depressions. 



o. Cross section of one of the preceding. 



q. Substance of the process made up mostly of adenoid tissue, containing many 

 deeply stained nuclei. 



