(ESOPHAGUS. . 179 



tunica propria there is always a certain amount of adenoid 

 tissue surrounding the ducts. 



In the mucosa superficial to the muscularis mucosse there 

 are other glands distinct from the mucous glands. These 

 occur in small groups situated mainly at the upper part of the 

 oesophagus and near the junction of the stomach and oesoph- 

 agus. They have been described by Riidinger, and later by 

 Schaffer. The subject has recently been worked over by 

 A. W. Hewlett, who applied the term superficial glands to 

 these structures. According to him, the glands are of the 

 branched tubular type. The tubules show in many places 

 cystic dilatations. The duct is lined with high columnar 

 epithelial cells with oval nuclei. In the acini the cells are 

 lower and the nuclei are more spherical and situated nearer the 

 base of the cell. Besides these cells, there are in the acini cells 

 identical with the parietal cells of the stomach. These vary 

 considerably in number. The cystic dilatations are similar to 

 those found in the mucous glands. According to Hewlett, the 

 superficial glands differ from the oesophageal mucous glands in 

 the following particulars : They are superficial to the muscu- 

 laris mucosse, and tend to occur in groups in certain places in 

 the oasophagus. The ducts are lined with a single layer of 

 columnar cells, and have no lymph oid tissue about them. 

 They frequently contain parietal cells and do not stain deeply 

 in the dyes used for mucin. 



The muscularis consists in the upper part of the oesophagus 

 of striated muscle ; in the lower parts, on the contrary, there 

 are two layers of smooth muscle. Of these, the inner is cir- 

 cular and the outer longitudinal. The striated muscle in the 

 upper part is continuous with the inferior constrictor of the 

 pharynx. It is found often extending down to the lower third 

 of the oesophagus, where it is replaced gradually by smooth 

 muscle. 



The tunica adventitia consists of loose connective tissue 

 binding the oesophagus to the surrounding structures. 



The blood-vessels are arranged like those of the mouth 

 cavity, the larger arteries and veins being situated in the sub- 



